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MG 2.1: PERIMETER & AREA RECTANGLES, SQUARES, TRIANGLES, CIRCLES
Defining and calculating
Goal/Objective:
• Students will be able to: Use formulas routinely for finding the perimeter and area of basic two- dimensional figures and the surface area and volume of basic three- dimensional figures, including rectangles, parallelograms, trapezoids, squares, triangles, circles, prisms, and cylinders.
When your family puts up a new fence around your home, how will they know how much
fencing they need?
PERIMETER
Perimeter• The perimeter of a figure is the
distance all the way around the figure.
Perimeter
• The perimeter is found by adding the lengths of the sides together.
Find the perimeter of the figures.
A.
B.
P = 24 mP = 21 cm
Perimeter of a Square
• A square is a figure with 4 equal sides.
• The perimeter can be found by adding all 4 sides together OR multiplying the side length by 4.
So, P = 4s
Find the perimeter of the squares using the formula P = 4s .
A.
B.
D.C.
P = 36 m P = 28 in.
P = 44 mm P = 20 cm
Perimeter of a Rectangle
• A rectangle is a figure with 4 sides. Opposite sides are equal.
• The perimeter can be found by adding all 4 sides together OR P = 2w + 2l
Find the perimeter of the rectangles using the formula P =
2w + 2l.A.
B.
D.
C.
P = 30 cm
P = 28 m
P = 54 mm P = 28 in.
If your parents want to put new carpet in your room, how
will they know how much carpet to buy?
AREA
Area• The area of a figure is the number of
square units that cover the surface of the closed figure.
Area
• A square unit is a unit that has 4 equal sides.
• For metric units, we say “units squared”. Ex: centimeters squared or cm2
• For U.S. Customary, we say “square units” Ex: square inches or sq. in.
Area
• The area of a figure is found by finding how many square units it takes to cover its surface.
Area of a Square
• The area of a square is found by finding how many square units it takes to cover its surface.
• Area of a square is: A = s x s or A = s2
Find the area of the squares using the formula A = s2.
A.
B.
A = 16 cm2 A = 25 sq. in.
Area of a Rectangle
• The area of a rectangle is found by finding how many square units it takes to cover its surface.
• Area of a rectangle formula is: A = l x w
Find the area of the rectangles using the formula A = l x w.
A.
B.
A = 24 cm2 A = 77 sq. in.
Perimeter of a Triangle
• Perimeter of Triangle= Sum of all sidesP= 5 in + 7in + 11 in
P= 23 in
11in
7in
5 in
Area of a Triangle
• Area of Triangle= 1/2 x (Base) x (Height)
or bh/2
Circumference of a Circle
Example:
Formulas to Memorize!
• Perimeter of a polygon: add up the lengths of the sides • Circumference of a circle: C=2 × π × r OR C= π × d • Area of Rectangle: A= bh• Area of Square: A=bh• Area of a triangle A = ½ × b × h• Volume of a rectangular solid: V=lwh• Area of a Circle= A=πr2