9-3C: Area of Composite Figures

9-3C: Area of Composite Figures Target: Find the areas of composite 2d figures.

Ex. 1: Find the Area of a Composite Figure • Find the area of the figure. • Separate the figure into a rectangle and triangle. Find the area of each and then add. • Area of Rectangle = bh • Area of Rectangle = (10)(6) = 60 • Area of Triangle = • Area of Triangle = = 8 • Add the two areas: 60+8 = 68 6 in 4 in 6 in 10 in

Practice This! 60 ft2 31.4 cm2 • Find the area of each figure. 8 ft 2.5 cm 10 ft 1.5 cm 4 ft 9.2 cm 12 ft

Ex. 2: Real World Example 28 ft • Find the area of the pool’s floor. • Separate the figure into a rectangle and trapezoid. • The area of the rectangle is 28x14 = 392. • The area of the trapezoid = 10 • 392+10 = 402 square feet. 14 ft 6 ft 4 ft 2 ft

Ex. 3: Find the area • The figure can be separated into a square and a rectangle. The shared rectangle however will be counted twice if the areas are added, sot he area of the small rectangle (6x7=42) must be subtracted from the total. • The area of the square is 12x12=144 • The area of the rectangle is 15x12=180 • The sum of the areas is 144+180=324 • Subtract the small rectangle 324-42=282 cm2 12 cm 6 cm 8 cm 12 cm 12 cm 15 cm

Practice This! • Find the area of the figures. 5m 1m 2m 4m 7.2 ft 6m 3.4 ft 2m

Classwork • Page 521 (1-13)

9-3C: Area of Composite Figures