1. Do Now

2. 4/20/2015 9-3 C Area of Composite Figures

3. To find the area of ANY composite figure, separate it into figures that you know how to solve for

4. Example 1
Find the area of the figure.

5. The area is 150 + 10 or 160 square centimeters.
Area of Rectangle Area of Triangle
The height of the triangle is 14 – 10 or 4 centimeters.
A = bh
A = 10 ● 15 or 150
The area is or 160 square centimeters.

6. Example 2
The diagram shows the dimensions of a window. Find the area of the window. Round to the nearest tenth.
The figure can be separated into a semicircle and a rectangle.
The height of the rectangle is 7.2 – 1.7, or 5.5 feet.

7. 2
or about
The area of the rectangle is 3.4 × 5.5 or 18.7 square feet.
The area of the window is or about 23.2 square feet.

8. Example 3 So, the area of the figure is 21 square meters.
Find the area of the figure.
The figure can be separated into two rectangles. The shared square, however, will be counted twice if the areas are added, so the area of the small square, 1 × 1, or 1 square meter, must be subtracted from the total.
The area of the top rectangle is 5 × 2 or 10 square meters.
The area of the bottom rectangle is 2 × 6 or 12 square meters.
The sum of the areas is or 22 square meters.
So, the area of the figure is 21 square meters.

9. Example 4
Find the area of the polygon.
1.7 cm
4.9 cm
1.3 cm
2.1 cm

10. 1.7 cm
4.9 cm
1.3 cm
2.1 cm
A = lw
A = lw
A = 4.9 • 1.7
A = 2.1 • 1.3
A = 8.33
A = 2.73
= 11.06
The area of the polygon is cm2.

11. Example 5
Find the area of the polygon.

12. A = bh 1 2 __
A = lw
A = • 28 • 12 1 2 __
A = 28 • 24
A = 168
A = 672
= 840
The area of the polygon is 840 ft2.

13. Patrick made a design. Use the coordinate grid to find its area.
Example 6
Patrick made a design. Use the coordinate grid to find its area.
Rectangle 1
l = 5, w = 5; A = 5 • 5 = 25 25 20
Rectangle 2 15
l = 10, w = 5; A = 10 • 5 = 50 10
Rectangle 3 5
l = 15, w = 5; A = 15 • 5 = 75 5 10 15 20 25
Rectangle 4
l = 20, w = 5; A = 20 • 5 = 100

14. = 250 square units.
The area of the design is 250 square units.

15. Exit Ticket 1. Find the area of the figure shown. 220 units2
2. Phillip designed a countertop. Use the coordinate grid to find its area.
30 units2

16. 1. Find the area of the figure.
A. 27 units B. 54 units2
C. 93 units2 D. 98 units2

17. Homework
Pg. 563 #1-20 Evens
Study for Chapter 9 Test