1. Composite Figures
All in One

2. Composite figures
Composite figures are two or more basic figures that can be combined.
5 cm
Find the perimeter of this figure, which consists of a semicircle and a rectangle.
7 cm
7 cm
5 cm
P=l+l+w+πd/2
P=(5)+(5)+(7)+π(7)/2
P= /2
P= or 11
P=28cm2

3. Composite figures
Now we need to find the perimeter of three sides of the rectangle at the bottom of the figure.
Total Perimeter = Circumference of top + Perimeter of bottom
= 11 cm + 17 cm
= 28 cm

4. Problem
Solution-we want to find the perimeter of the building. So we break the composite figure into three basic shapes-two rectangles and one square.
170
115
115
170
We find the length
Of the indented part of
Each rectangular shape
By subtracting 170 cm
From 210 cm to get 40 cm.
170
210
210
170 40 40
115
115
P = ( ) + ( )+ ( )
P = 1,300 cm

5. What is the perimeter of the composite figure?
5 cm cm
4 cm
3 cm cm
Find the lengths of the missing sides. Then add the side lengths.
Use the properties of congruent figures to find the missing measures.
The rectangle has a width of 4 cm.
The left side of the rectangle is 4 cm.
Add the lengths of the sides.
5 cm + 3 cm + 4 cm + 4 cm + 5 cm + 3 cm + 4 cm + 4 cm = 32 cm
The perimeter of the figure is 32 cm.
4 cm
4 cm
Hint: To determine the perimeter of a composite figure, measure the distance around the outside of the figure.

6. Bill is painting his basement floor.
The dimensions are:
2.5 m
If one can of paint will cover 3.5 m2, and each can of paint costs $15.25, what is his total cost?
3.2 m
1.8 m

7. A1 Atotal = A1 + A2 A = 2.3 x 2.5 + 3.1 x 1.5 A = 5.75 + 4.65 A2
a) Determine the total area.
2.3 m A1
Atotal = A1 + A2
2.5 m
A = 2.3 x x 1.5
A = A2
3.2 m
A = 10.4 m2
1.8 m

8. He will need about three cans of paint.
b) If one can of paint covers 3.5 m2, how many cans of paint will he need?
2.3 m
2.5 m
10.4 m2
3.2 m
He will need about three cans of paint.
1.8 m