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VIJAYA COLLEGE
RV ROAD, BASAVANAGUDI
BANGALORE - 04
BRIDGE COURSE FOR I SEMESTER STUDENTS OF B.Sc
DEPARTMENT OF MATHEMATICS
Department of Mathematics(UG), Vijaya College,RV Road, Bangalore-560004
2
RECAPITULATION OF BASIC CONCEPTS
We recapitulate several basic concepts, formulae and results which are
necessary for the future study in Mathematics.
ALGEBRA
SOME BASIC ALGEBRAIC FORMULAE:
1.(a + b)2 = a2 + 2ab+ b2 .
2.(a - b)2 = a2 - 2ab+ b2 .
3.(a + b)3 = a3 + b3 + 3ab(a + b).
4.(a β b)3 = a3 - b3 - 3ab(a - b).
5.(a + b + c)2 = a2 + b2 + c2 +2ab+2bc +2ca.
6.(a + b + c)3 = a3 + b3 + c3 +3a2b+3a2c + 3b2c +3b2a +3c2a +3c2b+6abc.
7.a2 β b2 = (a + b)(a β b).
8.a3 β b3 = (a - b) (a2 + ab + b2
).
9.a3 + b3 = (a + b) (a2 β ab+ b2
).
10.(a + b)2 β (a - b)2
= 4ab.
11.(a + b) 2 + (a β b)2
= 2(a2 + b2 ).
12.If a + b +c = 0, then a3 + b3 + c3 = 3abc.
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Theory of indices
The word βindicesβ is the plural form of the word βindexβ. In ππ , m is
called the index and a is called the base. ππ is called a power of a and it
obeys the following rules known as the laws of indices.
(i) ππ . ππ = ππ+π, (ii) ππ
ππ= ππβπ, (iii) (ππ)π = πππ, (iv) πβπ =
1
ππ,
(v) π0 = 1 (vi) β π π
(i.e., nth root of a) = π1
π (vii) ππ = ππ
then m = n.
Logarithms
If ππ₯ = π¦, then we say that the logarithm of y to the base a is x and is
written as logπ π¦ = π₯. If the base is 10,the logarithm is called as the
common logarithm and if the base is βeβ (known as the exponential constant
whose value is approximately2.70 the logarithm is called as the natural
logarithm.
Properties of logarithms
(i) logπ ππ = logπ π + logπ π, (ii) logππ
π= logπ π β logπ π , (iii)
logπ π = 1, (iv) logπ 1 = 0 (v) logπ ππ = π logπ π, (vi) logπ π =1
logπ π ;
logπ π₯ =logπ π₯
logπ π, k being a new base.
NOTE: log π₯ means logπ π₯. (natural logarithm)
Theory of equations
The quadratic equation ππ₯2 + ππ₯ + π = 0, the values of x satisfying the
equation are called as the roots or zeroes of the equation.
We have the formula for the roots of the above quadratic equation given by
π₯ =βπΒ±βπ2β4ππ
2π
Department of Mathematics(UG), Vijaya College,RV Road, Bangalore-560004
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Properties:
(i) Sum of the roots =βππβ and product of the roots = π πβ
(ii) if π2 β 4ππ is >0, the roots are real and distinct.
=0, the roots are real and coincident.
<0, the roots are imaginary and we denote π = ββ1 or
π2 = β1.
Square roots of unity: -1 and 1 are square roots of unity.
Cube roots of unity:1, 21 i 3 1 i 3
,2 2
are cube roots of unity.
where
Fourth roots of unity: -1, 1, i, -i are fourth roots of unity
Method of synthetic division
This method is useful in finding the roots of some equations which are of
degree greater than 2. The method is illustrated through examples.
Example 1: Solve: π₯3 + 6π₯2 + 11π₯ + 6 = 0
>> We have to first find a root by inspection which is done by taking value 1,
-1, 2, -2 etc. for x and identify the value which satisfies the equation. In this
example, putting x = - 1
we get β 1 + 6 -11 + 6 = 0. β΄ x = - 1is a root by inspection. We then proceed
as follows to find the remaining roots.
-1 1 6 11 6 All the coefficient are written.
0 -1 -5 -6 zero to be written bellow first coefficient & added
1 5 6 0 Resultant to be multiplied with the root -1 and added
2 31+Ο+Ο = 0 and Ο =1
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The existing figures 1, 5, 6 are to be associated with the quadratic: 1. π₯2 +
5. π₯ + 6 = 0 or (π₯ + 2)(π₯ + 3) = 0 β π₯ = β2,β3.Thus π₯ = β1,β2 β 3.
are the roots of the given equation.
Example 2 : Solve: π₯3 β 5π₯2 + 4 = 0
>> x = 1 is a root by inspection. Next we have as follows.
1 1 -5 0 4
0 1 -4 -4 β΄ π₯2 β 4π₯ β 4 = 0
1 -4 -4 0
By the quadratic formula
π₯ =β(β4)Β±β16+16
2=
4Β±β32
2=
4Β±4β2
2= 2(1 Β± β2 )
Thus 1, 2(1 Β± β2 ) are the roots of the given equation.
Progressions
(i) The sequence π, π + π, π + 2πβ¦β¦is called as the Arithmetic
Progression (A.P) whose general terms or the nth term is given by π’π = π +
(π β 1)π and sum to n terms is given by π π =π
2[2π + (π β 1)π] where βaβ
is the first term and βdβ is the common difference.
(ii) The sequence π, ππ, ππ2 β¦β¦. is called as the geometric Progression
(G.P) whose general term is given by πππβ1 and sum to n term is given by
π π =π(1βππ)
1βπ or π π =
π(ππβ1)
πβ1 according as r < 1 or r > 1 where βaβ is the first
term and βrβ is the common ratio. Also sum to infinity of this geometric
series when r <1 is a/(1-r).
(iii) The sequence 1
π,
1
π+π,
1
π+2πβ¦β¦β¦ .. is called as the Harmonic
Progression (H.P) whose general term is given by 1
π+(πβ1)π . In other words
a sequence is said to be an H.P if its reciprocals are in A.P.
(iv) If a ,A ,b are in A.P; a, G, B are in G.P and a, H, b are in H.P then A, G,
H are respectively called as the Arithmetic Mean (A.M), Geometric Mean
(G.M), Harmonic Mean (H.M) beteew a and b. Their value are as follows.
Department of Mathematics(UG), Vijaya College,RV Road, Bangalore-560004
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π΄ =π+π
2 , πΊ = βππ , H =
2ππ
π+π .
Mathematical Induction
This is a process of establishing certain results valid for positive integral
values of n. In this process we first verify the result when n=1 and then
assume the result to be true for some positive integer k. Later we prove the
result for n=k+1. The following results established by the principle of
mathematics induction will be useful.
(i) 1+2+3+4+β¦β¦β¦.+n = Ζ© n = π(π+1)
2.
(ii) 12 + 22 + 32 + β―β¦ .+π2 = βπ2 =π(π+1)(2π+1)
6.
(iii) 13 + 23 + 33 + β―β¦ .+π3 = βπ3 =π2(π+1)2
4.
Combinations
The notation πΆππ means, the number of combinations of n things taken r at a
time. That is selecting r things out of n things which is equivalent to
rejecting (n-r) things.
β΄ πΆππ = πΆπβπ
π where n β₯ r
The notation π! read as factorial n means the product of first n natural
numbers.
i.e., π! = 1.2.3.4β¦β¦ . (π β 1)(π). It may be noted that 0! = 1
We also have the formula: πΆππ =
π!
π!(πβπ)!. πΆπ + πΆπβ1 = πΆπ
(π+1)ππ
In particular, it is convenient to remember that πΆ0π = 1 , πΆ1
π = π, πΆ2π =
π(πβ1)
2!,
πΆ3π =
π(πβ1)(πβ2)
3! β¦. Etc
We also have the binomial theorem for a positive integer n given by
(π₯ + π)π = π₯π + πΆππ π₯πβ1π + πΆπ
π π₯πβ2π2 + β―β¦+ ππ
(x -a)n = xn
- nC1 xn-1 a + nC2 x
n-2 a2 - nC3 xn-3 a3 +------------+ (-1)r nCn a
n.
Department of Mathematics(UG), Vijaya College,RV Road, Bangalore-560004
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Matrices
A matrix is a rectangular arrangement of elements enclosed in a square or a
round bracket. If a matrix has m rows and columns then the order of the
matrix is said to be m Γ n and in particular if m = n the matrix is called a
square matrix of order n.
The transpose of a matrix π΄ is the matrix obtained by interchanging their
rows and columns and is usually denoted by π΄β². Also a square matrix π΄ is
said to be symmetric if π΄ = π΄β² and skew symmetric if π΄ = βπ΄β².
A square matrix having only non zero elements in its principal diagonal and
zero elsewhere is called a diagonal matrix. In particular if the non zero
elements are equal to 1, the matrix is called an identity matrix or unit matrix
denoted by πΌ .A matrix having all its elements equal to zero is called a null
matrix or zero matrix.
Example 1: [π 00 π
] ; [π 0 00 π 00 0 π
] are diagonal matrices.
Example 2: πΌ = [1 00 1
] ; [1 0 00 1 00 0 1
] are identity matrices.
Two matrices of the same order can be added or subtracted by adding or
subtracting the corresponding elements. If π΄is any matrix and k is a constant
then the matrix kπ΄ is the matrix obtained by multiplying every element of
π΄ by k.
The product of two matrices π΄ and π΅ can be found, if π΄ is of order m Γ n
and π΅ is of order n Γ p.
The product π΄π΅ will be a matrix of order m Γ p obtained by multiplying and
adding the row element of π΄ with the corresponding column elements of π΅.
Example 1: Let π΄ = [π1 π2 π3
π1 π2 π3] , π΅ = [
π1 π2
π1 π2
π1 π2
]
π΄ is of order 2Γ3, π΅ is of order 3Γ2 β΄ π΄π΅ is of order 2Γ2
Now π΄π΅ = [(π1π1 + π2π1 + π3π1) (π1π2 + π2π2 + π3π2)(π1π1 + π2π1 + π3π1) (π1π2 + π2π2 + π3π2)
]
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If A and B are two square matrices such that AB = I, then B is called as the
inverse of π΄ denoted by π΄β1. Thus AAβ1 = Aβ1A = I.
Determinants
The determinant is denoted for a square matrix π΄. It is usually denoted by
|π΄| and will represent a single value on expansion as follows.
|π ππ π
| = ππ β ππ.
|
π1 π2 π3
π1 π2 π3
π1 π2 π3
| = π1 |π2 π3
π2 π3| β π2 |
π1 π3
π1 π3| + π3 |
π1 π2
π1 π2|
i.e, = π1 (π2π3 β π3π2) β π2 (π1π3 β π3π1) +
π3 (π1π2 β π2π1)
Important properties of determinants
(i) The determinant can be expanded through any row or column as above
keeping in mind the sings +,β,+, β etc. as we move from one element to
the other starting from the first row or column.
(ii) The value of the determinant remains unaltered if the rows and columns
are interchanged.
(iii) The value of the determinant is zero if any two rows or columns are
identical or proportional.
(iv) The property of common factors is presented below.
|ππ1 ππ2
π1 π2| = π |
π1 π2
π1 π2| ; |
ππ1 π2
ππ1 π2| = π |
π1 π2
π1 π2|
Determinant method to solve a system of equations ( Cramerβs rule )
Consider, π1π₯ + π2π¦ + π3π§ = π1
π1π₯ + π2π¦ + π3π§ = π2
π1π₯ + π2π¦ + π3π§ = π3
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Let βπ₯= |
π1 π2 π3
π2 π2 π3
π3 π2 π3
| , βπ¦= |
π1 π1 π3
π1 π2 π3
π1 π3 π3
| , βπ§= |
π1 π2 π1
π1 π2 π2
π1 π2 π3
| & β=
|
π1 π2 π3
π1 π2 π3
π1 π2 π3
| .
Then π₯ =βπ₯
β , π¦ =
βπ¦
β , π§ =
βπ§
β . Here β is the coefficient determinant and
βπ₯, βπ¦ , βπ§ are the determinants obtained by replacing the coefficient of x ,y
,z respectively with that of constants in the R.H.S of the given equations.
Rule of cross multiplication
If , π1π₯ + π2π¦ + π3π§ = 0
π1π₯ + π2π¦ + π3π§ = 0
Then the proportionate values of x, y, z ie., x: y: z are given by π₯
|π2 π3π2 π3
|=
βπ¦
|π1 π3π1 π3
|=
π§
|π1 π2π1 π2
|.
Partial fractions
This is a method employed to convert an algebraic fraction π(π₯)
π(π₯)β into a
sum. The basic
requirement is that the degree of the numerator must be less than the degree
of the denominator , in which case the fraction is said to be a proper fraction.
If π(π₯)
π(π₯)β is proper fraction we factorize π(π₯) and resolve into partial
fractions appropriately which is based on the nature of the factors present in
the denominator.
We have the following cases.
(i) π(π₯)
(π₯βπΌ)(π₯βπ½)(π₯βπΎ)=
π΄
(π₯βπΌ)+
π΅
(π₯βπ½)+
πΆ
(π₯βπΎ).
(ii) π(π₯)
(π₯βπΌ)2(π₯βπ½)=
π΄
(π₯βπΌ)+
π΅
(π₯βπΌ)2+
πΆ
(π₯βπ½).
(iii) π(π₯)
(π₯βπΌ)(ππ₯2+ππ₯+π)=
π΄
(π₯βπΌ)+
π΅π₯+π
(ππ₯2+ππ₯+π).
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Where (ππ₯2 + ππ₯ + π)is a non factorizable quadratic and A ,B, C are all consants
to be found by first simplifying R.H.S taking L.C.M. Later we take convenient
values for x to obtain A, B ,C constants A, B, C can also be evaluated by comparing
the coefficient of various powers of x in L.H.S and R.H.S.
If π(π₯)
π(π₯)β is an improper fraction [ππππππ ππ π(π₯) β₯ ππππππ ππ π(π₯)]
we divide and rewrite using the known concept that,
π(π₯)
π(π₯)= (ππ’ππ‘ππππ‘) +
π ππππππππ
π·ππ£ππ ππ= π +
πΉ(π₯)
πΊ(π₯)
Here πΉ(π₯)
πΊ(π₯) will be a proper fraction .
NOTE: It is important to note that if needed a non factorizable quadratic
(ππ₯2 + ππ₯ + π) can be factorized involving constants like π + ππ or π + βπ
(in the factors0. Which being the roots of (ππ₯2 + ππ₯ + π)= 0.
Observe the following.
(i) (π₯2 + 25) = (π₯ + 5π)(π₯ β 5π)
(ii) (π₯2 β 5) = (π₯ + β5) (π₯ β β5)
(iii)(π₯2 β 2π₯ β 1) = (π₯ β 1 + β2) Here (1 Β± β2) are the roots of
(π₯2 β 2π₯ β 1) = 0 .
Following results are useful
i) f (x) 1 f (a) f (b)
(x a)(x b) a b x a x b
ii) 1 1 1 1
(x a)(x b) a b x a x b
iii)
2 2 2 2 2 2 2 2 2 2
1 1 1 1
(x a )(x b ) a b x a x b
TRIGONOMETRY
Area of a sector of a circle = 21r
2 .
Arc length, S = r ΞΈ.
Department of Mathematics(UG), Vijaya College,RV Road, Bangalore-560004
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Trigonometric ratios
Let ABC be a right angled triangle and let π΄οΏ½ΜοΏ½π΅ = π. The side AB is called
as the opposite side of π, BC is the adjacent side and AC is the hypotenuse.
The six trigonometric ratios are defined as follows. A
C B
π πππ =π΄π΅
π΄πΆ πππ π =
π΅πΆ
π΄πΆ π‘πππ =
π΄π΅
π΅πΆ πππ πππ =
π΄πΆ
π΄π΅ π πππ =
π΄πΆ
π΅πΆ πππ‘π =
π΄πΆ
π΄π΅
(The expanded form of these are respectively sine, cosine, tangent, cosecant,
secant and cotangent,)
Inter relations:
π πππ =1
πππ πππ ; πππ π =
1
π πππ ; π‘πππ =
1
πππ‘π ; π‘πππ =
π πππ
πππ π .
πππ πππ =1
π πππ ; π πππ =
1
πππ π ; πππ‘π =
1
π‘πππ ; πππ‘π =
πππ π
π πππ .
Identities:
(i) π ππ2π + πππ 2π = 1
(ii)1+π‘ππ2π = π ππ2π
(iii) 1+πππ‘2π = πππ ππ2π
Radian measure: π πππππππ = 180π (Degrees can be converted into
radians and vice-versa).
Example 1: 45π = 45 Γπ
180=
π
4πππππππ
Example 2: 2π
3=
2Γ180
3= 120π
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Trigonometric ratios for certain standard angles
π 0π 30π
(π 6β )
45π
(π 4β )
60π
(π 3β )
90π
(π 2β )
180π
(π)
360π
(2π)
150
(π 12β )
750
(5π 12β )
π πππ 0 1 2β 1 β2β β3 2β 1 0 0 β3 β 1
2β2
β3 + 1
2β2
πππ π 1 β3 2β 1 β2β 1 2β 0 β1 1 β3 + 1
2β2
β3 β 1
2β2
π‘πππ 0 1 β3β 1 β3 β 0 0 β3 β 1
β3 + 1
β3 + 1
β3 β 1
πππ‘π, π πππ, πππ πππ are respectively the reciprocals of π‘πππ, πππ π, π πππ.
Allied angles
Trigonometrical ratios of 90 Β± π, 180 Β± π, 270 Β± π, 360 Β± π in terms of
those of πcan be found easily by the following rule known as A βS βT βC
rule.
(i) When the angle is 90 Β± π ππ 270 Β± π the trigonometrical ratio changes
from sine to cosine and vice-versa. Also βtanβ & βcotβ, βsecβ & βcosecβ.
(ii) When the angle is 180 Β± π, 360 Β± π the trigonometrical ratio remains
the same⦠i.e, sinsin, coscos etc.
(iii) In each case the sign + or β is premultiplied by the A βS βT βC quadrant
rule.
S A A : All ratios are +ve in the I quadrant.
II (90π β 180π) I (0π β 90π) S : βSinβ is + ve in the II quadrant.
T C T : βTanβ is + ve in the III quadrant.
III (180π β 270π) IV (270π β 360π) C : βCosβ is + ve in IV quadrant.
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NOTE: sin(βπ) = βπ πππ , cos(βπ) = πππ π, sin(π2π + π) = π πππ , cos(π2π +
π) = πππ π
Example 1: sin(90π β π) = πππ π, cos(90π + π) = βπ πππ
sin(180 β π) = π πππ, tan(180 + π) = π‘πππ.
Example 2: sin(135π) = sin(90π + 45π) = πππ 45π = 1 β2β
tan(315π) = tan(270π + 45π) = βπππ‘45π = β1
cos(225π) = cos(180π + 45π) = βπππ 45π = β1 β2β
sin(750π) = sin(2 Γ 360π + 30π) = π ππ30π = 1 2 β
Compound angle formulae
(i) sin(π΄ + π΅) = π πππ΄ πππ π΅ + πππ π΄ π πππ΅
Sin(π΄ β π΅) = π πππ΄ πππ π΅ β πππ π΄ π πππ΅
(ii) cos(π΄ + π΅) = πππ π΄ πππ π΅ β π πππ΄ π πππ΅
cos(π΄ β π΅) = πππ π΄ cosπ΅ + π πππ΄ π πππ΅
(iii) tan(π΄ + π΅) =π‘πππ΄+π‘πππ΅
1βπ‘πππ΄π‘πππ΅
Tan(π΄ β π΅) =π‘πππ΄βπ‘πππ΅
1+π‘πππ΄π‘πππ΅
Formulae to convert a product into sum or difference
(iv) π πππ΄ πππ π΅ =1
2 [sin(π΄ + π΅) + sin(π΄ β π΅)]
(v) πππ π΄ π πππ΅ =1
2 [sin(π΄ + π΅) β sin(π΄ β π΅)]
(vi) πππ π΄ πππ π΅ =1
2 [cos(π΄ + π΅) + cos(π΄ β π΅)]
(vii) π πππ΄ π πππ΅ = β1
2 [cos(π΄ + π΅) β cos(π΄ β π΅)]
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Particular cases of formulae
π ππ2π΄ = 2π πππ΄πππ π΄
π πππ΄ = 2sin (π΄ 2)cos (π΄ 2)ββ
πππ 2π΄ = πππ 2π΄ β π ππ2π΄
πππ 2π΄ = 1 β 2π ππ2π΄
πππ 2π΄ = 2πππ 2π΄ β 1
πππ π΄ = πππ 2(π΄ 2) β π ππ2(π΄ 2β ) β
πππ π΄ = 1 β 2π ππ2 π΄ 2β
πππ π΄ = 2πππ 2 π΄ 2β β 1
tan 2A =2
2 tan A
1 tan A ,
π‘πππ΄ =2π‘πππ΄ 2β
1βπ‘ππ2π΄ 2β
π ππ3π΄ = 3π πππ΄ β 4π ππ3π΄
πππ 3π΄ = 4πππ 3π΄ β 3πππ π΄
tan 3A=
3
2
3tan A tan A
1 3tan A
.
We have, π ππ2π΄ =2π‘πππ΄
1+π‘ππ2π΄ ππ π πππ΄ =
2π‘πππ΄ 2β
1+π‘ππ2π΄ 2β
πππ 2π΄ =1βπ‘ππ2π΄
1+π‘ππ2π΄ ππ πππ π΄ =
1βπ‘ππ2π΄ 2β
1+π‘ππ2π΄ 2β
Almost used formulae in problem:
1 + cos 2A =22cos A or
2cos A =1
(1 cos 2A)2
.
1- cos 2A = 22sin A or
2sin A =1
(1 cos 2A)2
,
1 + sin 2A=2(sin A cos A) and 1- sin 2A=
2(cos A sin A) =2(sin A cos A) ,
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Formulae to convert a sum or difference into a product
(i) π πππΆ + π πππ· = 2π πππΆ+π·
2 πππ
πΆβπ·
2
(ii) π πππΆ β π πππ· = 2πππ πΆ+π·
2 π ππ
πΆβπ·
2
(iii) πππ πΆ + πππ π· = 2πππ πΆ+π·
2 πππ
πΆβπ·
2
(iv) πππ πΆ β πππ π· = β2π πππΆ+π·
2 π ππ
πΆβπ·
2
Relation between the sides and angles of a triangle
In any triangle ABC a, b ,c respectively denotes the sides AC, CA, AB.
These three sides along with angles οΏ½ΜοΏ½, οΏ½ΜοΏ½, οΏ½ΜοΏ½ from the six elements of the
triangle. We give two important formulae relating these elements.
(i) Sine formula: If ABC is a triangle inscribed in a circle then π
π πππ΄=
π
π πππ΅=
π
π πππΆ= 2π, π being the circum radius.
(ii) Cosine formula : In any triangle ABC, π2 = π2 + π2 β 2ππ πππ π΄;
π2 = π2 + π2 β 2ππ πππ π΅; π2 = π2 + π2 β 2ππ πππ πΆ.
(iii)Projection Rule: a = b cosC +c cosB
b = c cosA +a cosC
c = a cosB +b cosA
(iv)Tangents Rule: B C b c A
tan cot2 b c 2
,
C A c a B
tan cot2 c a 2
,
A B a b C
tan cot2 a b 2
.
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Half angle formulae:
A (s b)(s c)sin
2 bc
,
A s(s a)cos
2 bc
,
A (s b)(s c)tan
2 s(s a)
.
B (s a)(s c)sin
2 ac
,
B s(s b)cos
2 ac
,
B (s a)(s c)tan
2 s(s b)
.
C (s a)(s b)sin
2 ab
,
C s(s c)cos
2 ab
,
C (s a)(s b)tan
2 s(s c)
.
Area of triangle ABC = s(s a)(s b)(s c) , where 2s = a + b + c.
Area of triangle ABC = 1 1 1
bcsin A acsin B absin C2 2 2
.
In any triangle ABC, we have
1. sin2A + sin2B + sin2C = 4sinAsinBsinC
2. sin2A + sin2B - sin2C = 4cosAcosBsinC
3. cos2A + cos2B + cos2C = -1- 4cosAcosBcosC
4. cos2A + cos2B - cos2C = 1- 4sinAsinBcosC
Inverse Trigonometric functions:
Function Domain Range
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y = sin-1x
y = cos-1x
y = tan-1x
y = cot-1x
y = sec-1x
y = cosec-1x
1 1x
1 1x
x
x
1 1x or x
1 1x or x
2 2y
0 y
2 2y
0 y <
0 ,2
excepty y
, 02 2
excepty y
General Solution of Trignometric Equations:
1. Sin = k, where -1β€ k β€ 1
Sin = sin , where k = sin
Gen. solun. is
2. cos = k, where -1β€ k β€ 1
cos = cos , where k = sin
Gen. solun. is
3. tan = k, where - β€ k β€
( 1)nn
2n
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tan = tan , where k = tan
Gen. solun. is where n β¬ Z
All the cases n = 0, 1, 2, 3, 4,---
COMPLEX TRIGONOMETRY
A number of the from π§ = π₯ + ππ¦ where x, y are real numbers and π = ββ1
or π2 = β1 is called a complex number in the Cartesian form x is called the
real part of z and y is called imaginary part of z. π§Μ = π₯ β ππ¦ is called the
complex conjugate of z.
Polar form of π§ = π₯ + ππ¦: The point (x , y) is plotted in the XOY plane and
let OP= r, PM is drawn perpendicular onto the x β axis.
Y P(x, y)
r
ΞΈ ππ
0 M X
From the figure OM= x, PM = Y, ποΏ½ΜοΏ½π = π
Further πππ π =π₯
π , π πππ =
π¦
π i.e., π₯ = π πππ π, π¦ = π π πππ.
Squaring & adding : π₯2 + π¦2 = π2 or π = βπ₯2 + π¦2
Dividing : π‘πππ = π¦ π₯ ππβ π = tanβ1(π¦ π₯β ).
π§ = π₯ + ππ¦ = π(πππ π + π π πππ) is called as the polar form of z. further it
may be noted that πππ = πππ π + π π πππ. thus π§ = ππππ is the polar form of z
where r is called the βmodulusβ of z and ΞΈ is called the βamplitudeβ or
βargument of z. Symbolically we have,
π = |π§| = βπ₯2 + π¦2 ; π = πππ π§ = arg π§ = tanβ1 π¦ π₯β .
ΞΈ
n
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Also we have πβππ = πππ π β π π πππ and hence we can write, πππ + πβππ =
2πππ π and
πππ β πβππ = 2π π πππ.
De-Moivreβs Theorem : If n is a rational number ( positive or negative
integer ,fraction) then (πππ π + π π πππ)π = cosππ + π sin ππ.
Expansion of πππππ, πππππ, ππππππππππ where m, n are positive
integers
The method is explained through two examples as it becomes easy to grasp
the procedure involved.
Example 1: To expand πππ 6π₯
>> Let π‘ = πππ π₯ + π π πππ₯ β΄ π‘π = cos ππ₯ +
π sin ππ₯
Also 1
π‘= πππ π₯ β π π πππ₯ β΄
1
π‘π= cos ππ₯ β
π sin ππ₯
Adding and subtracting these we get,
π‘ +1
π‘= 2πππ π₯β¦β¦β¦(1) π‘ β
1
π‘= 2π sin π₯ β¦β¦ . (2)
π‘π +1
π‘π= 2πππ ππ₯ β¦β¦(3)
π‘π β1
π‘π= 2π sin ππ₯ β¦β¦(4)
NOTE : Forming equation (1) to(4) is a common step in all the expansions
mentioned.
To expand πππ 6π₯, we need to rise (1) to the power 6 and write it in the form
(2 πππ π₯)6 = (π‘ +1
π‘)6
Expanding R.H.S by the binomial theorem we have,
26πππ 6π₯ = π‘6 + πΆ16 π‘5.
1
π‘+ πΆ2
6 π‘4.1
π‘2+ πΆ3
6 π‘3.1
π‘3+ πΆ4
6 π‘2.1
π‘4+ πΆ5
6 π‘.1
π‘5+
1
π‘6
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But π56 = π1
6 = 6 ; π46 = π2
6 =6Γ5
1Γ2= 15 ; π3 =6 6Γ5Γ4
1Γ2Γ3= 20
β΄ 26πππ 6π₯ = (π‘6 +1
π‘6) + 6 (π‘4 +
1
π‘4) + 15(π‘2 +
1
π‘2) + 20
Using equation (3) in the R.H.S by taking n = 6, 4, 2 we have,
26πππ 6π₯ = 2 cos 6π₯ + 6(2 πππ 4π₯) + 15 (2πππ 2π₯) +20
β΄ πππππ =π
ππ (ππ¨π¬ππ + πππ¨π¬ππ + ππππ¨π¬ππ + ππ)
Example 2: To expand π ππ5π₯ πππ 2π₯
>> Rise (2) to the power 5, (1) to the power 2 and multiply.
β΄ (2ππ πππ₯)5(2πππ π₯)2 = (π‘ β1
π‘)5
(π‘ +1
π‘)2
i.e., (25π5π ππ5π₯)(22πππ 2π₯) = (π‘5 β πΆ15 π‘4.
1
π‘+ πΆ2
5 π‘3.1
π‘2β πΆ3
5 π‘2.1
π‘3+
πΆ45 π‘.
1
π‘4β
1
π‘5) Γ (π‘2 +1
π‘2+ 2)
Here π5=π2 Γ π2 Γ π = β1 Γ β1 Γ π = π
But π45 = π1
5 = 5 , π35 = π2 =
5Γ4
1Γ2
5 = 10.
Thus we have, 27ππ ππ5π₯πππ 2π₯ = (π‘7 β1
π‘7) β 3 (π‘5 β1
π‘5) + (π‘3 β1
π‘3) + 5 (π‘ β1
π‘)
Using (4) in the R.H.S by taking n=7, 5, 3 and 1 we have
27ππ ππ5π₯πππ 2π₯ = 2π sin7xβ3(2π π ππ5π₯) + 2ππ ππ3π₯ + 5 (2π π πππ₯)
Dividing by 2i throughout we get,
β΄ ππππππππππ =π
ππ (π¬π’π§ππ β ππ¬π’π§ ππ + π¬π’π§ππ + π ππππ)
HYPERBOLIC FUNCTIONS
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We have already said that βeβ whose value is approximately 2.7 is called the
exponential constant. Further if logπ π¦ = π₯ then π¦ = ππ₯ is called the
exponential function. Hyperbolic function are defined in terms of
exponential functions as follows.
Sine hyperbolic of x = sinh π₯ =ππ₯βπβπ₯
2.
Cosine hyperbolic of x = cosh π₯ =ππ₯+πβπ₯
2.
Also, tanh π₯ =sinhπ₯
coshπ₯ ; coth π₯ =
1
tanh π₯=
coshπ₯
sinhπ₯
sech π₯ =1
cosh π₯ ; πππ ππβ π₯ =
1
sinh π₯
Important hyperbolic identities
(i) πππ β2π β π ππβ2π = 1 (iv) π ππβ2π + πππ β2π = cosh 2π
(ii)1+π‘ππ2π = π ππ2π (v)2 sinhπ coshπ = sinh2π
(iii) 1+πππ‘2π = πππ ππ2π
Relationship between trigonometric and hyperbolic functions
We have sin π₯ =πππ₯βπβππ₯
2π & cos π₯ =
πππ₯+πβππ₯
2
Now sin( ππ₯) =πβπ₯βππ₯
2π= (β1)
(ππ₯βπβπ₯)
2π= π2
ππ₯βπβπ₯
2π
i.e., sin(ππ₯) = π .ππ₯βπβπ₯
2 β΄ π ππ(ππ₯) = π π ππβ π₯
Also cos(ππ₯) =πβπ₯+ππ₯
2= cosh π₯ β΄ cos ππ₯ = πππ βπ₯
From these we can deduce the remaining four relations in respect of tan(ix), cot(ix)
sec(ix) & cosec(ix).
Calculus
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Function
Let x and y be two variables which take only real values. If there is a relation
between x and y such that for a given x it is possible to find a corresponding
value of y, then y is said to be a function of x which is symbolically
represented as y = f(x). This means that y depends on x. x is called the
independent variable and y is called the dependent variable.
For example y = f(x) = 3x +1 means that y is a function of x.
If x = 0 then y = f(0) = 3Γ0+1 = 1;
If x =2, y = f(2) = 3Γ2 +1 = 7 etc.
For every x we get only one corresponding value of y. Such a function is
called a single valued function.
Now consider the Example: π¦2 = π₯2 + 4 or π¦ = Β±βπ₯2 + 4
When x = 0, y = Β± β4 ie., y = +2 or y = -2
When x = 1, y = Β± β5 ie., y = +β5 or y = -β5 etc.
For every x we get more than one of y.
Such a function is called a many valued function.
Further if y = 3x+1 then y -1= 3x or x = 1
3 (y-1).
Also in the case of π¦2 = π₯2 + 4 we have π₯2 = π¦2 β 4 or π₯ = Β±βπ¦2 β 4 .
It should be observed that in these two examples we have expressed x in
terms of y and such a function is called an inverse function symbolically
represent as x = πβ1(y) read as, x is equal to f inverse y.
π[πβ1(π₯)] = π₯ = πβ1[π(π₯)]. Observe the following functions and their
corresponding inverse function.
(i) π πππ¦ = π₯ or π¦ = sinβ1 π₯
(ii) π‘πππ¦ = π₯ or π¦ = tanβ1 π₯
(iii) πππ βπ¦ = π₯ or π¦ = πππ ββ1π₯
(iv)logπ π¦ = π₯ or π¦ = ππ₯
It may be noted that sin (sinβ1 π₯), tanβ1(π‘πππ₯) = π₯, log(ππ₯) = π₯ = πππππ₯
etc.
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Limits
Consider y = f(x) and when x =a, y = f(a). sometimes f(a) assumes forms
like 0
0 ,
β
β , β β β,00 , 1β etc which are all undefined, In mathematics these
are called indeterminate forms.
Observe the example π¦ =π₯2β1
π₯β1
When x = 1 y = 0
0 which is undefined.
We can rewrite y in the form, y = (π₯β1)(π₯+1)
(π₯β1)
Suppose x β 1we can cancel the factors (x-1).
β΄ When x = 1, y = 0
0 and when x β 1, y = x+1.
Instead of taking x = 1 we shall give values for x which are very near to 1
(little less than 1 or little more than 1) and tabulate them:
x 0.9 0.99 0.999 1.1 1.01 1.001 β¦..
y =
x+1
1.9 1.99 1.999 2.1 2.01 2.001 β¦β¦
From the table it can be observed that when the value of x is little less or
more than 1, the value of y is little less or more than 2. But y has no value
when x = 1. This is equivalent to saying that then when x is closer and closer
to 1, y is closer and closer to 2. In other words we say that the limit of y as x
tends to 1 is equal to 2 and is symbolically represented as follows
limπ₯β1
π¦ = 2 or limπ₯β1
π₯2β1
π₯β1= 2
Also if y = 1
π₯ it is obvious that as x increases y decreases and this can be
represented in the limit form as limπ₯ββ
1
π₯= 0
The following are some of the established standard limits.
(i) limπ₯βπ
(π₯πβππ
π₯βπ) = πππβ1, n is any rational number
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(ii) limπ₯β0
π πππ₯
π₯= 1
(iii) limπ₯β0
π‘πππ₯
π₯= 1
(iv) limπββ
(1 +π₯
π)π
= ππ₯
(v) limπ₯ββ
π₯1 π₯β = 1
(vi)limπ₯β0
(1 + π₯)1
π₯β = π or limπ₯ββ
(1 +1
π₯)π₯
= π
Simple illustrations
Example 1: limπ₯β2
π₯5β32
π₯β2 this is in the
0
0 form.
= limπ₯β2
π₯5β32
π₯β2= 5 Γ 25β1 = 80, using (i)
Example 2: limπ₯β0
π ππππ₯
π ππππ₯β¦ . .
0
0 form
= limπ₯β0
π ππππ₯
π₯π ππππ₯
π₯
= limπ₯β0
π(π ππππ₯
ππ₯)
π(π ππππ₯
ππ₯)=
πΓ1
πΓ1=
π
π by using (ii)
Example 3: limπββ
3π+4
5π+1β¦ .
β
β form
= limπββ
π(3+4
π)
π(5+1
π)=
3+0
5+0=
3
5 β΅
1
πβ 0 as π β β
Differentiation
Let y = f(x) be a continuous explicit function of x. Any change in x result in
a corresponding change in y. Let x change to x + Ξ΄x and let the
corresponding change in y be y + Ξ΄y. Ξ΄x, Ξ΄y are respectively called the
increments in x, y.
β΄ we have y = f(x) and y + Ξ΄y = f(x + Ξ΄x)
Also y +Ξ΄y βy = f(x +Ξ΄x) βf(x)
i.e., Ξ΄y = f(x+Ξ΄x) βf(x)
Then limπΏπ₯β
πΏπ¦
πΏπ₯= lim
πΏπ₯β0
π(π₯+πΏπ₯)βπ(π₯)
πΏπ₯ when exists is called as the differential
coefficient or the derivative of y with respect to x (w.r.t.x) and is denoted by ππ¦
ππ₯ or πβ²(π₯) here
π
ππ₯ is called the differential operator ( +, -, Γ, Γ·) usually
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denoted by D. ππ¦
ππ₯ means
π
ππ₯(π¦) which is to be understood as the derivative of
y w.r.t x.
Example: Let π¦ = π₯π, n is any real number
β΄ π¦ + πΏπ¦ = (π₯ + πΏπ₯)π
Subtracting we get πΏπ¦ = (π₯ + πΏπ₯)π β π₯π
limπΏπ₯β
πΏπ¦
πΏπ₯= lim
πΏπ₯β0
(π₯ + πΏπ₯)π β π₯π
πΏπ₯
As Ξ΄x 0, x + Ξ΄x x. putting t = x+ Ξ΄x we have,
πβ²(π₯) =ππ¦
ππ₯= lim
πΏπ₯β0
π‘πβπ₯π
π‘βπ₯= ππ₯πβ1,By using standard limit (i)
Thus πβ²(π₯) =ππ¦
ππ₯=
π
ππ₯(π₯π) = ππ₯πβ1.
The following table gives a list of derivatives established for standard functions.
Differentiation Formulae Differentiation of Functions
1. 1( )nnd x
nxdx
1( ) ( ) . ( )
n nd df x n f x f x
dx dx
2. ( )x
xd ee
dx ( ) ( )[ ] . ( )f x f xd d
e e f xdx dx
3. ( ) log .x xda a a
dx ( ) ( )[ ] . ( )f x f xd d
a a f xdx dx
4. 1(log )e x
dx
dx
1[log ( )] . ( )
( )e
d df x f x
dx f x dx
5. 1
2
dx
dx x
1( ) . ( )
2 ( )
d df x f x
dx dxf x
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6. 2
1 1d
dx x x
2
1 1( )
( ) [ ( )]
d df x
dx f x dxf x
7. 1
1
n n
d n
dx x x
1
1( )
[ ( )] [ ( )]n n
d n df x
dx dxf x f x
8. sin cosd
x xdx
sin ( ) cos ( ) . ( )d d
f x f x f xdx dx
9. cos sind
x xdx
cos ( ) sin ( ) . ( )d d
f x f x f xdx dx
10. 2tan secd
x xdx
2tan ( ) sec ( ) . ( )d d
f x f x f xdx dx
11. 2cot secd
x co xdx
2cot ( ) sec ( ) . ( )d d
f x co f x f xdx dx
12. sec sec tand
x x xdx
sec ( ) sec ( ) tan ( ) . ( )d d
f x f x f x f xdx dx
13. sec sec cotd
co x co x xdx
sec ( ) sec ( )cot( ) ( )d d
co f x co f x x f xdx dx
14. sinh coshd
x xdx
sinh ( ) cosh ( ) . ( )d d
f x f x f xdx dx
15. cosh sinhd
x xdx
cosh ( ) sinh ( ) . ( )d d
f x f x f xdx dx
16. 2tanh secd
x h xdx
2tanh ( ) sec ( ) . ( )d d
f x h f x f xdx dx
17. 2coth secd
x co h xdx
2coth ( ) sec ( ) . ( )d d
f x co h f x f xdx dx
18. sec sec tanhd
hx hx xdx
, sec ( ) sec ( ) tanh ( ) . ( )d d
hf x h f x f x f xdx dx
19. π
ππ₯(πππ ππβπ₯) = βπππ ππβπ₯ πππ‘βπ₯
π
ππ₯(πππ ππβπ(π₯)) = βπππ ππβπ(π₯)πππ‘βπ(π₯).
ππ(π₯)
ππ₯
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20. 1
2
1sin
1
dx
dxx
1
2
1sin ( ) . ( )
1 ( )
d df x f x
dx dxf x
21. 1
2
1cos
1
dx
dxx
1
2
1cos ( ) . ( )
1 ( )
d df x f x
dx dxf x
22. 1
2
1tan
1
dx
dx x
1
2
1tan ( ) . ( )
1 ( )
d df x f x
dx dxf x
23. 1
2
1cot
1
dx
dx x
1
2
1cot ( ) . ( )
1 ( )
d df x f x
dx dxf x
24. 1
2
1sec
1
dx
dxx x
1
2
( )1sec ( ) .
( ) ( ) 1
d f xdf x
dx dxf x f x
25. 1
2
1sec
1
dco x
dxx x
1
2
( )1sec ( ) .
( ) ( ) 1
d f xdco f x
dx dxf x f x
26. 1
2
1sinh
1
dx
dxx
1
2
1sinh ( ) . ( )
1 ( )
d df x f x
dx dxf x
27. 1
2
1cosh
1
dx
dx x
1
2
1cosh ( ) . ( )
( ) 1
d df x f x
dx dxf x
28. 1
2
1tanh
1
dx
dx x
1
2
1tanh ( ) . ( )
1 ( )
d df x f x
dx dxf x
29. 1
2
1coth
1
dx
dx x
1
2
1coth ( ) . ( )
1 ( )
d df x f x
dx dxf x
30. 1
2
1sec
1
dh x
dxx x
1
2
( )1sec ( ) .
( ) 1 ( )
d f xdh f x
dx dxf x f x
31. 1
2
1sec
1
dco h x
dxx x
1
2
( )1sec ( ) .
( ) ( ) 1
d f xdco h f x
dx dxf x f x
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Rule of differentiation
Rule β 1: Function of a function rule or chain rule
If y = f(u) where u = g(x) then
ππ¦
ππ₯=
ππ¦
ππ’.ππ’
ππ₯= πβ²(π’). πβ²(π₯)
In other words, if y = f[g(x)] then ππ¦
ππ₯= πβ²[π(π₯)]. πβ²(π₯)
Further if y = f[g{h(x)}] then ππ¦
ππ₯= πβ²[π{β(π₯)}]. πβ²{β(π₯)}. ββ²(π₯)
Example: π¦ = log(π πππ₯) , π¦ = sin(π sinβ1 π₯), π¦ = tanβ1 π3π₯ , π¦ = ππ cosβ1 π₯
Rule β 2: Product rule
π
ππ₯(π’π£) = π’
ππ£
ππ₯+ π£
ππ’
ππ₯ ie., (π’π£)β² = π’π£β² + π£π’β²
Example: π¦ = ππ₯ log π₯ , π¦ = βsin π₯ . tan (log π₯).
Rule β 3: Quotient rule
π
ππ₯(π’
π£) =
π£ππ’
ππ₯βπ’
ππ£
ππ₯
π£2 ie., (
π’
π£) =
π£π’β²βπ’π£β²
π£2
Example: π¦ =log π₯
π₯, π¦ =
1+π ππ3π₯
1βπ ππ3π₯.
Differentiation of implicit functions
If x and y are connected by a relation then the process of finding the
derivative of y w.r.t x is called as the differentiation oh implicit function.
In other words, given f(x, y) = c we need to find ππ¦
ππ₯ treating y as a function
of x.
We have already said that π
ππ₯[π{π(π₯)}] is equal to πβ²{π(π₯)}. πβ²(π₯). This is
equivalent to saying that
π
π π[π(π) = πβ²(π)
π π
π π
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Example:π₯π πππ¦ + π₯2 + π¦2 = π¦πππ π₯ ,π₯2 + π¦2 + π2.
Differentiation of parametric functions
If x and y are function of a parameter t we need to find the derivative of y
w.r.t. x ie., given x = f(t) , y = g(t) we have to find ππ¦
ππ₯
The rule is ππ¦
ππ₯=
ππ¦
ππ‘
ππ₯
ππ‘β and it is obvious that
ππ¦
ππ₯ is a function of t.
Example: π₯ = ππ‘2& π¦ = 2ππ‘, π₯ = π(πππ π + ππ πππ) &
π¦ = π(π πππ β ππππ π)
Logarithmic differentiation
Suppose we have the explicit function in the form π¦ = [π(π₯)]π(π₯) or an
implicit function in the form [π(π₯)]π(π¦) = π (say)then we have to first take
logarithms on bothsides and then differentiate w.r.t x for computing ππ¦
ππ₯ If the
index is a variable then it becomes necessary to employ logarithmic
differentiation for computing the derivative. Sometimes we employ this
method otherwise also to make the differentiation work simpler.
Example: π¦ = ππ₯, ππ = πππππ ππ
Differentiation by using trigonometric substitution and formulae
Sometimes the given function will be in such a form that it will be difficult
to differentiate in the direct approach. In such cases we have to think of a
suitable substitution leading to a trigonometric formulae that simplifies the
given function considerably, thereby we can differentiate easily.
Example: π¦ = sinβ1 (2π₯
1+π₯2) , π¦ = tanβ1 (1βπ₯
1+π₯) put π₯ = tanπ
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INTEGRATION
Integration is regarded as the reverse process of differentiation (anti
differentiation). For example, we know that π
ππ₯(sin π₯) = cos π₯. This is
equivalent to saying that the integral of cos π₯ with respect to x is equal to
sin π₯. Since the derivative of a constant is always zero we can as well write, π
ππ₯(sin π₯ + π) = cos π₯ or equivalently integral of cos π₯ w.r.t. x is sin π₯ + π.
The symbol Κ stands for the integral. Thus in general we can say that if π
ππ₯[π(π₯) + π] = πΉ(π₯) then β«πΉ(π₯)ππ₯ = π(π₯) + π, c being the arbitrary
constant.
A list of Integration of some standard functions
1
, wheren 11
nn x
x dxn
log(cosec cot )cosec
ax axax dx
a
1logdx x
x 2 tan
secax
ax dxa
x xe dx e 2 cotcos
axec ax dx
a
log
xx a
a dxa
sec
sec tanax
ax ax dxa
sin cosxdx x sec
sec cotco ax
co ax ax dxa
cos sinxdx x sinh coshx dx x
tan log(sec ) logcosx dx x x cosh coshx dx x
cot log(sin )x dx x tanh logcoshx dx x
sec log(sec tan )x dx x x 2sec tanhh x dx x
cosec log(cosec cot )x dx x x 2cos cothech xdx x
2sec tanx dx x sec tanh sechx xdx hx
2cos cotec xdx x cosec coth cosechx xdx hx
sec tan secx xdx x 1 1
2
1sin cos
1
dx x x
x
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sec cot secco x xdx co x 1 1
2
1tan cot
1dx x x
x
cossin
axax dx
a 1 1
2
1sec cos
1
dx x ec x
x x
sincos
axax dx
a 1
2
1sinh
1
dx x
x
log(sec ) logcostan
ax axax dx
a a 1
2
1cosh
1
dx x
x
log(sin )cot
axax dx
a 1
2
1sec
1
dx h x
x x
log(sec tan )sec
ax axax dx
a
Note: The above results can easily be verified by differentiating the R.H.S of the
results.
Some methods of integration
Method 1: β«πβ²(π₯)
π(π₯)ππ₯ = log π(π₯). If the numerator is the derivative of the
denominator then the integral is equal to logarithm of the denominator.
Further if π
ππ₯[π(π₯)] = ππβ²(π₯), where k is a constant then
β«πβ²(π₯)
π(π₯)ππ₯ =
1
πβ«
ππβ²(π₯)
π(π₯)ππ₯ =
1
πlog π(π₯).
Example: β«1
3π₯+4ππ₯ , β«
1
π‘πππ₯(1+π₯2)ππ₯, β«
1
π₯ log π₯ππ₯, β«
2π₯+3
3π₯+1
Method 2: Integration by substitution
In this method a suitable substation is taken to reduce the given integral to a
simpler form in the new variable and integrate accordingly. Taking substation is only
by judgment in case of simple problems, though we have specific substitutions for
some specific form of integrals.
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Example:β«(3π₯+4)ππ₯
β3π₯2+8π₯+5 , β«
π₯2
β1βπ₯6ππ₯ .
Remark: Trigonometric function, hyperbolic functions will also serve as
substitutions in the evaluation of certain standard integrals and these integrals are
given later. They will be highly useful.
Method 3: Integration by parts (Product rule)
β«π’π£ ππ₯ = π’ β«π£ ππ₯ β β«β«π£ ππ₯ . π’β² ππ₯
It should be noted that this rule is not applicable for integrals of product of any two
functions. However if the first function is a polynomial in x and the integral of the
second function is known the rule can be tried. In such a case we also have a
generalized product rule known as the Bernoulliβs rule which is as follows.
β«π’π£ ππ₯ = π’ β«π£ ππ₯ β π’β² β«β«π£ ππ₯ ππ₯ + π’β²β² β«β«β«π£ ππ₯ ππ₯ ππ₯ β β― . .
Example: β«π₯πππ 3π₯ ππ₯, β« log π₯ ππ₯, β«(π₯3 + π₯ + 1)π2π₯ππ₯.
Method 4: Method of partial fractions
The method is narrated in the Algebra section. After resolving the function
π(π₯) π(π₯)β into partial functions we have to integrate term by term.
Method 5: Integration by using trigonometric formulae
Various integrals involving products of sine and cosine terms and terms like
π ππ2π₯, πππ 2π₯, π ππ3π₯, πππ 3π₯ etc. can be found by using various trigonometric
formulae as given in the Trigonometry section. These formulae converts product
into a sum.
Example: β« πππ 23π₯ ππ₯, β« π ππ4π₯ πππ 2π₯ ππ₯.
Standard integrals
With the help of the method discussed earlier, the following standard integrals are
obtained and they will be highly useful.
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1)
2 2
axax e
e sin(bx + c)dx = [asin(bx + c) + bcos(bx + c)]a b
2) 2 2
axax e
e cos(bx + c)dx = [acos(bx + c) - bsin(bx + c)]a + b
Note: (1) &(2) are obtained by parts.
Integration by substitution
1. n+1
n [f(x)][f(x)] . f (x)dx =
n +1
2. n+1
n 1 (ax + b)(ax + b) dx =
a n +1
3. 1
sin(ax + b)dx = - cos(ax + b)a
4. 1
cos(ax + b)dx = sin(ax + b)a
5. 1 1
tan(ax + b)dx = log sec(ax + b) = - log cos(ax + b)a a
6. 1
cot(ax + b)dx = log sin(ax + b)a
7. 1
sec(ax + b)dx = log sec(ax + b) + tan(ax + b)a
8. 1
cosec(ax + b)dx = log cosec(ax + b) - cot(ax + b)a
9. 1
2 2
-1dx xtan
a aa x (by putting x = a tanΞΈ)
10. 1
, where
2 2
dx a + xlog a x
2a a - xa x (by partial fractions)
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11. 1
, where
2 2
dx x - alog a x
2a x + ax a (by partial fractions)
12.
2 2
-1dx xsin
aa x
(by putting x = a sinΞΈ)
13.
2 2
-1dx xsinh
aa x
(by putting x= a sinhΞΈ)
14.
2 2
-1dx xcosh
ax a
(by putting x = a coshΞΈ)
15.
2
2 2 2 2 -1x a xa x dx a x + sin
a 2 a (by putting x = a sinΞΈ)
16.
2
2 2 2 2 -1x a xa x dx a x + tan
a 2 a (by putting x = a sinhΞΈ)
17.
2
2 2 2 2 -1x a xx a dx x a - cosh
a 2 a(by putting x = a coshΞΈ)
Note: sinβ1 π₯ πβ = log(π₯ + βπ₯2 + π2)
cosβ1 π₯ πβ = log(π₯ + βπ₯2 β π2)
We now proceed to give a few method where the standard integrals are being used.
Method 6: Integration by completing the square
This method is applicable for integrals of the type:
1ππ₯2 + ππ₯ + π,β 1
βππ₯2 + ππ₯ + πβ ,βππ₯2 + ππ₯ + π.
We consider ππ₯2 + ππ₯ + π and write it in the form π(π₯2 + ππ₯ πβ + π πβ ). We then
express it in the form π[(π₯ Β± πΌ)2 Β± π½2], πΌ and π½ being constants, we complete the
integration by making use the standard integrals.
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Example: β«ππ₯
π₯2+6π₯+25, β«
ππ₯
βπ₯2+6π₯+25, β« βπ₯2 + 6π₯ + 25ππ₯.
Method 7: Integral of the types:
ππ₯ + π
ππ₯2 + ππ₯ + π,
ππ₯ + π
βππ₯2 + ππ₯ + π , (ππ₯ + π)βππ₯2 + ππ₯ + π
In all the three cases we first express the numerator (linear term) as l (derivative of
the quadratic) + m. where l, m are constants to be found. That is to find l and m such
that ππ₯ + π = π(2ππ₯ + π) + π
Example: β«(4π₯+5)ππ₯
4π₯2+12π₯+5, β«
(4π₯+5)ππ₯
β4π₯2+12π₯+5, β«(4π₯ + 5)β4π₯2 + 12π₯ + 5ππ₯.
A few more types of integral along with substitution for the purpose of
integration is as follows.
1. β«ππ₯
(ππ₯+π)βππ₯+πβ¦ . ππ’π‘ (ππ₯ + π) = π‘2
2. β«ππ₯
(ππ₯+π)βππ₯2+ππ₯+πβ¦ . ππ’π‘ =
1
π‘
3. β«ππ₯
π π πππ₯+π πππ₯+πβ¦ . ππ’π‘ tan(π₯ 2β ) = π‘ and use the result π πππ₯ =
2π‘
1+π‘2,
πππ π₯ =1βπ‘2
1+π‘2 Also dx will become
2ππ‘
1+π‘2
4.β«ππ₯
π2πππ₯2π₯+π2π ππ2π₯+πβ¦. multiply and divide by π ππ2π₯ and then put tanx = t
In all the above cases we arrive at a quadratic in t.
Definite integrals
We define β« π(π₯)ππ₯ = π(π) β π(π)π₯=π
π₯=π where π(π₯) = β«π(π₯)ππ₯
Observe the following examples
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β« π₯2ππ₯ =2
1[π₯3
3]1
2
=23
3β
13
3=
8
3β
1
3=
7
3.
β« πππ π₯ ππ₯ = [π πππ₯]0π 2β
= sin (π 2)β β π ππ0 = 1 β 0 = 1.π 2β
0
Properties of Definite Integral
1. ( ) ( )
b b
a a
f x dx f t dt
2. ( ) ( )
b a
a b
f x dx f x dx
3. ( ) ( ) ( )
b c b
a a c
f x dx f x dx f x dx , where a < c < b
4.0 0
( ) ( )
a a
f x dx f a x dx
5. 0
2 ( ) , ( ) ,. ( ) ( )( )
0 ( ) ,. ( ) ( )
aa
a
f x dx if f x is even i e f x f xf x dx
if f x is odd i e f x f x
6.
2
00
2 ( ) , (2 ) ( )( )
0 (2 ) ( )
aa
f x dx if f a x f xf x dx
if f a x f x
Y
π¦ = π(π₯)
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0 a b X
Note: Geometrically β« π(π₯)ππ₯π
π represents the area bounded by the curve
π¦ = π(π₯), the x β axis and the ordinates x = a, x = b.
Application of Integration
I. Area bounded by the curve y = f(x), X-axis and x = a, x = b is given by
Area = ( )
b b
a a
y dx f x dx
II. Area bounded by the curve x = g(y), Y-axis and y = c, y = d is given by
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Area = ( )
b b
a a
x dy g y dy
III. Area bounded by the curve y = f(x), y = g(x), X-axis and x = a, x = b is
given by
Or
Area bounded between the curves y = f(x), y = g(x) intersecting at x = a, x = b
is given by
Area = ( ) ( )
b b
a a
f x dx g x dx
VECTOR ALGEBRA
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Vector is a quantity having both magnitude and direction. Scalar is a
quantity having only magnitude. For example, force, velocity, acceleration
are vector quantities. Density, mass are scalar quantities.
A vector with magnitude equal to one is called a unit vector. The line
segment joining a given point to the origin is called as the position vector of
that point.
Representation of a vector in three dimensions
Let OX and OY be two mutually perpendicular straight lines. Draw a line
OZ perpendicular to the XOY plane. In other words OX, OY, OZ are said to
from three mutually perpendicular straight lines. Let P be any point in space
and from P draw PM perpendicular to the XOY plane. Also draw MA
perpendicular to the X β axis, MC perpendicular to the Z β axis and PB
perpendicular to the Y β axis.
If OA = x, OB = y, OC = z then the coordinates of P = (x, y, z). Y
P (x, y, z)
A X
O
C M
Z
Suppose we take three points respectively on the coordinate axes at a
distance of 1 unit from the origin O then these will have coordinates
respectively ( 1, 0, 0), (0, 1, 0) and (0, 0, 1) . the associated line segments are
the unit vectors: οΏ½ΜοΏ½ = (1,0,0) , πΜ = (0,1,0) and οΏ½ΜοΏ½ = (0,0,1) along the
coordinate axes and are called the basic unit vectors.
We have (x, y, z) = x(1, 0, 0) + y(0, 1, 0) + z(0, 0, 1)
The vector representation of the point P is written in the standard form ππββββ β =
π = π₯οΏ½ΜοΏ½ + π¦πΜ + π§οΏ½ΜοΏ½
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Magnitude of π = distance between O ( 0, 0, 0) and P ( x, y, z) =
β(π₯ β 0)2 + (π¦ β 0)2 + (π§ β 0)2 = βπ₯2 + π¦2 + π§2
β΄ |π | = βπ₯2 + π¦2 + π§2 is the magnitude of π . Also οΏ½ΜοΏ½ = π |π |β is always a
unit vector.
οΏ½βοΏ½ = 0π + 0π + 0π is called the null vector.
Definition and properties
(1) Dot and cross products : Let π΄ and οΏ½βοΏ½ be any two vectors subtending an
angle ΞΈ between them. Also let οΏ½ΜοΏ½ represent the unit vector perpendicular to
the plane containing the vectors π΄ and οΏ½βοΏ½ (i.e., perpendicular to both π΄ and
οΏ½βοΏ½ ). Then we have
π΄ . οΏ½βοΏ½ = |π΄ ||οΏ½βοΏ½ |πππ π (Scalar quantity)
π΄ Γ οΏ½βοΏ½ = |π΄ ||οΏ½βοΏ½ |π ππποΏ½ΜοΏ½ (Vector quantity) where π΄ , οΏ½βοΏ½ , οΏ½βοΏ½ forms a right handed
system.
(2) Angle between the vectors π΄ & οΏ½βοΏ½ : From the definition of the dot product
we have
πππ π =π΄ οΏ½βοΏ½
|π΄ ||οΏ½βοΏ½ | .Further the vectors are perpendicular if π = π
2β or
cos π = πππ π2β = 0 => π΄ . οΏ½βοΏ½ = 0 i.e., to say that π΄ is perpendicular to B
if π΄ . οΏ½βοΏ½ = 0
(3)Properties : (i) π΄ . οΏ½βοΏ½ = οΏ½βοΏ½ . π΄ ; π΄ Γ οΏ½βοΏ½ = β(π΄ Γ οΏ½βοΏ½ )
(ii) οΏ½ΜοΏ½. οΏ½ΜοΏ½ = πΜ. πΜ = οΏ½ΜοΏ½. οΏ½ΜοΏ½ = 1
(iii) οΏ½ΜοΏ½ Γ οΏ½ΜοΏ½ = πΜ Γ πΜ = οΏ½ΜοΏ½ Γ οΏ½ΜοΏ½ = 0β
(iv) οΏ½ΜοΏ½ Γ πΜ = π,βββ πΜ Γ οΏ½ΜοΏ½ = π,Μ οΏ½ΜοΏ½ Γ οΏ½ΜοΏ½ = πΜ
(v)οΏ½ΜοΏ½. πΜ = πΜ. οΏ½ΜοΏ½ = οΏ½ΜοΏ½. οΏ½ΜοΏ½ = 0
(4) Analytic expressions for the dot and cross products
If π΄ = π1οΏ½ΜοΏ½ + π2πΜ + π3οΏ½ΜοΏ½ and οΏ½βοΏ½ = π1 οΏ½ΜοΏ½ + π2πΜ + π3οΏ½ΜοΏ½
Then π΄ . οΏ½βοΏ½ = π1π1 + π2π2 + π3π3
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π΄ Γ οΏ½βοΏ½ = |οΏ½ΜοΏ½ πΜ οΏ½ΜοΏ½π1 π2 π3
π1 π2 π3
|
(5) Scalar triple product or Box product
π΄ . (οΏ½βοΏ½ Γ πΆ ) Denoted by [π΄ , οΏ½βοΏ½ , πΆ ] is called as the scalar triple product or the
box product of the vectors π΄ , οΏ½βοΏ½ , πΆ
Properties:
(i) π΄ . (οΏ½βοΏ½ Γ πΆ ) = (π΄ Γ οΏ½βοΏ½ ). πΆ
(ii) π΄ . (οΏ½βοΏ½ Γ πΆ ) = οΏ½βοΏ½ . (πΆ Γ π΄ ) = πΆ . (οΏ½βοΏ½ Γ π΄ )
(iii) [π΄ , οΏ½βοΏ½ , πΆ ] is equal to the value of coefficient determinant of the vectors
π΄ , οΏ½βοΏ½ , πΆ
(iv) If any two vectors are identical in a box product then the value is equal
to zero. In such a case we say that the vectors are coplanar.
(6) Expressions for the vector triple product
(i) π΄ Γ (οΏ½βοΏ½ Γ πΆ ) = (π΄ . πΆ )οΏ½βοΏ½ β (π΄ . οΏ½βοΏ½ )πΆ
(ii) (π΄ Γ οΏ½βοΏ½ ) Γ πΆ = (π΄ . πΆ )οΏ½βοΏ½ β (οΏ½βοΏ½ . πΆ )π΄
Simple illustration: Given π΄ = 2π + π β 2π, οΏ½βοΏ½ = 3π β 4π,
Let us compute π΄ . οΏ½βοΏ½ , π΄ Γ οΏ½βοΏ½ and the angle between π΄ and οΏ½βοΏ½
>> π΄ . οΏ½βοΏ½ = (2π + π β 2π). (3π β 4π)
π΄ . οΏ½βοΏ½ = (2)(3) + (1)(0) + (β2)(β4) = 14
π΄ Γ οΏ½βοΏ½ = |π π π2 1 β23 0 β4
| = π(β4 β 0) β π(β8 + 6) + π(0 β 3)
= β4π + 2π β 3π
If ΞΈ is the angle between π΄ and οΏ½βοΏ½ then
πππ π =π΄ οΏ½βοΏ½
|π΄ ||οΏ½βοΏ½ |=
14
β22 + 12 + (β2)2β32 + (β4)2=
14
(3)(5)=
14
15
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πππ π =14
15 ππ cosβ1 (
14
15) = π.
COORDINATE GEOMETRY OF TWO DIMENSIONS
Coordinate representation Y
Q B P
y y
πβ² C A X
-y -y
R D S
πβ²
The coordinate representation of the points shown in the figure with reference
to the origin
O = (0, 0) is as follows.
P = (x, y) Q = ( - x, y) R = (- x, - y) S = ( x, - y) A = ( x, 0) B
= (0, y)
C = ( - x, 0) D = ( 0, - y)
Some basic formulae : Let A = (x1, y1) and B = (x2, y2)
(i) Distance AB = β(π₯2 β π₯1)2 + (π¦2 β π¦1)
2 (Distance formula)
(ii) Coordinates of the point P dividing the line joining AB in the ratio π:π
is given by(ππ₯2Β±ππ₯1
πΒ±π ππ¦2Β±ππ¦1
πΒ±π) [section formula]
The sign is positive if P divides AB internally and the sing is negative if P
divides AB externally.
Particular case : (a) The coordinates of the midpoint of AB is given by
(π₯2+π₯1
2 ,
π¦2+π¦1
2)
[ π = π in the external division formula]
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(b) The coordinates of the point dividing AB in the ratio 1 : k internally is
given by (π₯2+ππ₯1
1+π ,
π¦2+ππ¦1
1+π) . This coordinate is regarded as the coordinate of
any arbitrary point lying on the line AB.
Locus : The path traced by a point which moved according to alaw (certain
geometrical conditions) is called as the locus.
Straight line
If a straight line make an angle ΞΈ with the positive direction of the x β axis
then m = tanΞΈ is called as the slope or the gradient of the straight line.
NOTE: If y = f(x) be the equation of a curve then πβ²(π₯) =ππ¦
ππ₯ represents the
slope of the tangent at a point P(x, y) on it.
The equation representing different kinds of straight lines along with figures
is as follows.
(1) x = 0 and y = 0 respectively represent the equation of the y β axis and the
x β axis.
π₯ = π1& π¦ = π2 are respectively the equations of a line parallel to the y β
axis and the equation of a line parallel to the x β axis. Y
x = 0 y = π2
y = 0 X
x = π1
(2) y = mx is the equation of a line passing through the origin having slope m. In
particular y = x is the equation of a line through the origin subtending an angle 45π
with the x β axis (slope = 1).
Y y = mx
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y = x
X
(3) π₯
π+
π¦
π= 1 (intercept form) is the equation of a line having x intercept a and y
intercept b. That is the line passing through (a, 0) and (0, b).
Y
X
(4) y = mx + c is the equation of a straight line having slope m and an intercept c
on the y β axis.
(5) π¦ β π¦1 = π(π₯ β π₯1) is the equation of a straight line passing through the
(π₯1, π¦1) having slope m.
(6) π¦βπ¦1
π₯βπ₯1=
π¦2βπ¦1
π₯2βπ₯1 is the equation of a straight line passing through the points
(π₯1, π¦1) & (π₯2, π¦2). Also π =π¦2βπ¦1
π₯2βπ₯1 is slope of a straight line joining the points
(π₯1, π¦1) & (π₯2, π¦2).
(7) Ax +By +C = 0 is the equation of a straight line in the general form i.e., π¦ =
βπ΄
π΅π₯ β
πΆ
π΅ and comparing with y = mx + c we can say that the slope (m) = β
π΄
π΅=
β πππππ.ππ π₯
πππππ.ππ π¦.
Angle : Angle ΞΈ between the straight lines having slope π1and π2 is given by
π‘πππ =π1βπ2
1+π1π2 Further the line are perpendicular if π = π
2β which implies
π‘πππ = β and we must have 1 + π1π2 = 0 or π1π2 = β1. Also if the lines are
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parallel then ΞΈ = 0which implies tan ΞΈ = 0 and hence we have, π1 β π2 =
0 ππ π1 = π2
βLines are perpendicular if the product of the slope is β 1 and lines are parallel if
the slopes are equalβ
Length of the perpendicular: The length of the perpendicular from an external
point (π₯1, π¦1) onto the line ax + by + c = 0 is given by |ππ₯1+ππ¦1+π|
βπ2+π2.
Circle
The equation of the circle with centre (a, b) and radius r is (π₯ β π)2 +
(π¦ β π)2 = π2. In particular if origin is the centre of the circle then the
equation is π₯2 + π¦2 = π2
The equation of the circle in its general form is given by, π₯2 + π¦2 + 2ππ₯ +
2ππ¦ + π = 0 whose centre is(βπ,βπ) and radius is βπ2 + π2 β π
Conics
If a point moves such that its distance from a fixed point (known as the focus)
bears a constant ratio with the distance from a fixed line (known as the
directrix) the path traced by the point (locus of the point) is known as a conic.
The constant ratio is known as the eccentricity of the conic usually denoted by
βeβ. the conics are respectively called as parabola, ellipse and hyperbola
according as e = 1, e < 1 and e >1. Also it may be noted that an asymptote is a
tangent to the curve at infinity.
Some useful information about the conics with their equation in the Cartesian
and parametric forms along with their shapes are given.
(1) Parabola
π¦2 = 4ππ₯ (Symmetrical about the x β axis) ; π₯ = ππ‘2, π¦ = 2ππ‘
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π₯2 = 4ππ¦ (Symmetrical about the y β axis) ; π¦ = ππ‘2, π₯ = 2ππ‘
General forms of parabola : (π¦ β π)2 = 4π(π₯ β β); (π₯ β β)2 = 4π(π¦ β π)
Y
Y π¦2 = 4ππ₯
πβ² π₯2 = 4ππ¦
S X X
Focus=S=(a, 0) Focus=πβ²=(0, a)
(2) Ellipse
π₯2
π2+
π¦2
π2= 1 ; π₯ = ππππ π, π¦ = π π πππ
Length of the major and minor axis are respectively 2a and 2b S(Focus)=(ae,
0), πβ²(Focus) =(- ae, 0)
Coordinates of foci (Β± ae, 0) = (Β±βπ2 β π2 ,0)
Y
π₯2
π2+
π¦2
π2= 1
X
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(3) Hyperbola
π₯2
π2β
π¦2
π2= 1; π₯ = π π πππ, π¦ = π π‘πππ
S (Focus)=(ae, 0), πβ²(Focus) =(- ae, 0)
Coordinates of foci (Β± ae, 0) = (Β±βπ2 + π2 ,0)
It may also be noted that = π2 ;π₯ = ππ‘, π¦ = π π‘β is the equation of a curve
known as the rectangular hyperbola.
Y
πβ² S
X
AREA, VOLUME, SURFACE AREA
Circle: Area = r2; Circumference = 2 r.
Ellipse: Area = Οab
Square: Area = x2; Perimeter = 4x.
Rectangle: Area = xy ; Perimeter = 2(x + y).
Triangle: Area = (base)(height) ; Perimeter = 2s = a + b + c.
Area of equilateral triangle = 3
4a2
.
1
2
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Area = s(s a)(s b)(s c)
Name of solid Volume Lateral or
curved surface
area
Total surface
area
1. Cube π3 4π2 6π2
2. Cuboid ππβ 2(π + π)β 2(ππ + πβ + βπ)
3. Cylinder ππ2β 2ππβ 2ππ(π + β)
4. Cone 1 3β . ππ2β πππ ππ(π + π)
5. Sphere 4 3β . ππ3 - 4ππ2
Where in the case of cone l is the slant height connected by the relation
π‘2 = π2 + β2.
Three Dimensional Geometry:
Type equation here.
Direction cosines and direction ratios of a line:
If a line makes an angle Ξ±, Ξ² and Ξ³ with the co-ordinate axes, then l=cosΞ±, m=cosΞ² and
n=cosΞ³ are called direction cosines of the line and a, b, c are direction ratios given by the
relations
O Y
Z
X
P(x,y,z)
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π
π =
π
π =
π
π
Direction cosines and direction ratios of a line passing through two points (x1,y1,z1) &
(x2,y2,z2)
Directions ratios x2-x1, y2,z2 β z1 and direction cosines are
2 1 2 1 2 1
2 2 2 2 2 2 2 2 2
2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1
, ,( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( )
x x y y z z
x x y y z z x x y y z z x x y y z z
EQUATION LINE IN THREE DIMENSIONS:
1 1 1
(vector form)
Cartesian form of the equation is
I. Equation of a line thriugh and parallel to b is r = b
x-x y-y z-z= =
a b c
a a r rrr r
1 1 1
2 1 2 1 2 1
(vector form)
Cartesian form of the equation is
II. Equation of a line through two points and b is r = (b- )
x-x y-y z-z= =
x -x y -y z -z
a a ar rrr r r
1 2 3 1 2 3
1 2 1 2 1 2
2 2 2 2 2 2
1 2 3 1 2 3
cos =
III. Angle between two vectors ( , , ) and b ( , , ) is given by
a a b b c c
a a a a b b b
a a a b b b
rr
1 2 3 1 2 3
1 2 3
1 2 3
1 2 3 1 2 3
Note: 1. condition for two vectors ( , , ) and b ( , , ) are parallel is
2. condition for two vectors ( , , ) and b ( , , ) are parallel is
a a a a b b b
a a a
b b b
a a a a b b b
rr
rr
1 2 1 2 1 2 a a +b b +c c = 0
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1 1 2 2
1 2 2 1
1 2
IV. Shortest distance between two skew lines b and b
(b b ) ( ) d=
b b
a a is
a a
r rr r
r r r r
r r
1 2
2 1
V. Distance between the parallel lines b and b
b ( ) d=
b
a a is
a a
r rr r
r r r
r
EQUATION OF PLANE:
(vector form)
Cartesian form of the equation is
ΛI. Equation of a plane in normal form r n = d
, where l, m, n are d.cs
of the normal and 'd' is length of the normal.
lx my nz d
rg
1 1 1
(vector form)
Cartesian form of the equation is
II. Equation of a plane perpendicular to the given vector and passing
through a point is (r-a) N = 0
A(x-x )+B(y-y )+C(z-z )my+nz=0, where A,
rr rg
B, C
are d.rs of the normal Nr
1 1 1
2 1 2 1 2 1
3
(vector form)
Cartesian form of the equation is
III. Equation of a plane passing through three non-collinear points a, b, c
is (r-a) [(b-a) (c-a) = 0
x-x y-y z-z
x -x y -y z -z
x -
rr r
rr r r r rg
1 3 1 3 1
0
x y -y z -z