1. What is Trigonometry? Trigonometry is a branch of
mathematics that studies triangles and the relationships between
their sides and the angles between these sides.
2. 3 Right Triangle A triangle in which one angle is equal to
90 is called right triangle. The side opposite to the right angle
is known as hypotenuse. AB is the hypotenuse The other two sides
are known as legs. AC and BC are the legs Trigonometry deals with
Right Triangles
3. The origin of the terms cosine and tangent was much later.
The cosine function arose from the need to compute the sine of the
complementary angle. The name cosinus originated with Edmund
Gunter. In 1674, the English Mathematician Sir Jonas Moore first
used the abbreviated notation cos COSINE AND SINE Edmund Gunter
(1581 1626)
4. Sine of angle B A B 90o C P H B sin(B) = = P H perpendicular
hypotenuse
5. Cosine of angle A cos(A) = = B C base hypotenuse 90o
6. THE TRIGONOMETRIC RATIOS Tangent tan Opposite Adjacent
Cotangent cot Adjacent Opposite Secant sec Hypotenuse Adjacent
Cosecant cosec Hypotenuse Opposite Function Abbr. Description Sine
sin Opposite Hypotenuse Cosine cos Adjacent Hypotenuse The
Cosecant, Secant, and Cotangent are the Reciprocals of the Sine,
Cosine,and Tangent respectively .
7. THE TRIGONOMETRIC VALUES Angle A 0o 30o 45o 60o 90o sin A 0
1 2 1 2 3 2 1 cos A 1 3 2 1 2 1 2 0 tan A 0 1 3 1 3 Not Defined
cosec A Not Defined 2 2 2 3 1 sec A 1 2 3 2 2 Not Defined cot A Not
Defined 3 1 1 3 0
