1. Warm Up
Problem of the Day
Lesson Presentation
Lesson Quizzes

2. Warm Up Find each area. Round to the nearest tenth, if necessary.
1. a rectangle with length 10 cm and width 4 cm
2. a parallelogram with base 18 ft and height 12 ft
3. a triangle with base 16 cm and height 8 cm
4. a circle with radius 5 in.
40 cm2
216 ft2
64 cm2
78.5 in2

3. Problem of the Day
Four squares are placed in a row, adjacent to one another. The square on the far left is 12 inches on a side. The perimeter of each of the other squares is half of the one to its left. What is the perimeter of the combined figure?
69 in. 3 3

4. Sunshine State Standards
MA.6.G.4.2 Find the…areas of composite two-dimensional figures…using various strategies.
Also MA.6.A.3.4

5. Additional Example 1A Finding the Area of Composite Figures by Adding
Find the shaded area. Round to the nearest tenth, if necessary.
Divide the figure into a rectangle and a trapezoid.
area of the rectangle:
A = bh
A = 12 • 6
A = 72 m2

6. Additional Example 1 Continued
Find the shaded area. Round to the nearest tenth, if necessary.
area of the trapezoid:
2 m
8 m
A = h(b1 + b2) 1 2 __
2 m
4 m
6 m
6 m
A = 2(4 + 2) 1 2 __
A = (12) 1 2 __
A = 6 m2
Add the area of the rectangle and the area of the trapezoid.
total area: A = = 78 m2.

7. Check It Out: Example 1
Find the shaded area. Round to the nearest tenth, if necessary.

8. Check It Out: Example 1 Continued
Find the shaded area. Round to the nearest tenth, if necessary.
Area of rectangle: 9 × 8 = 72 yd
Area of triangle: (2)(9) = 9 yd
Area of composite figure: = 81 yd 2 1 _

9. Subtract the area of the triangle from the area of the rectangle.
Additional Example 2: Finding the Area of Composite Figures by Subtracting
5 ft
Find the shaded area.
6 ft
9 ft
Subtract the area of the triangle from the area of the rectangle.
12 ft
Area of the rectangle:
Area of the triangle:
A = bh 1 2 __
A = bh
A = 12 • 9 = 108 ft2
A = • (6)(7) 1 2 __
A = • 42 = 21 ft2 1 2 __
Shaded area:
A = 108 – 21 = 87 ft2

10. area of rectangle: A = lw = 16 8 = 128
Check It Out: Example 2
9 in.
Find the shaded area.
5 in.
8 in.
16 in.
area of rectangle: A = lw = = 128
area of triangle: A = bh = (5 7) = (35) = 17.5
area of shaded area: A = = in 1 1 1 _ 2 2 2 2

11. Additional Example 3: Landscaping Application
6 ft
What is the area of the room floor shown in the figure? Round to the nearest tenth.
12 ft
12 ft
6 ft
18 ft
To find the area, divide the composite figure into a square, a rectangle, and a semicircle.

12. Additional Example 3 Continued
6 ft
Area of the square:
12 ft
12 ft
A = s2
6 ft
A = 62 = 36 ft2
18 ft
Area of the rectangle:
Area of the semicircle:
A = r2 1 2 __
A = bh
A = 18 • 6 = 108 ft2
A  • 3.14 • (9)2 1 2 __
A  (254.34)
 ft2 1 2 __

13. Additional Example 3 Continued
6 ft
What is the area of the room floor shown in the figure? Round to the nearest tenth.
12 ft
12 ft
6 ft
18 ft
Area of the room:
A = = ft2
The area of the room is approximately ft2.

14. Check It Out: Example 3
What is the area of the stage floor shown in the figure? Round to the nearest tenth.

15. Check It Out: Example 3 Continued
area of top rectangle: A = lw = 5 · 5 = 25
area of large rectangle: A = lw = 15 · 5 = 75
area of semicircle: A =  r ≈ (3.14 · 7.5 )
≈ (176.6) = 88.3
total area: A = = ft 2 1 _ 2 1 _ 2 2 2

16. Lesson Quizzes
Standard Lesson Quiz
Lesson Quiz for Student Response Systems

17. Lesson Quiz: Part l
Find the shaded area of each figure. Round to the nearest tenth, if necessary. 1. 2. 3.
111 ft2
5 ft
45.9 in2
188.9 mm2

18. Lesson Quiz: Part ll
4. The figure gives the dimensions of a backdrop for a school play. Find the area of the backdrop.
97 ft2

19. Lesson Quiz for Student Response Systems
1. Find the shaded area of each figure. Round to the nearest tenth, if necessary.
A. 40 ft B ft2
C. 14 ft2 D ft2
5 ft
8 ft
2 ft