Main Idea and New Vocabulary Key Concept: Area Formulas Example 1: Find the Area of a Composite Figure Example 2: Real-World Example Example 3: Find the Area of a Shaded Region Lesson Menu

Find the area of composite figures. Main Idea/Vocabulary

Key Concept

Find the Area of a Composite Figure Find the area of the composite figure. Round to the nearest tenth. This area can be separated into a rectangle and a semicircle. Example 1

Find the Area of a Composite Figure Area of a rectangle Area of a semicircle A = bh A = 12 • 6 A = 72 Example 1

Find the Area of a Composite Figure Answer: The area of the figure is about 72 + 14.1 or 86.1 square centimeters. Example 1

Find the area of the composite figure. Round to the nearest tenth. A. 100.0 in2 B. 167.9 in2 C. 240.0 in2 D. 349.9 in2 Example 1 CYP

DOG HOUSE One side of a dog house is composed of a square and a triangle. How much wood is needed for this side of the dog house to the nearest tenth of a square foot? The sides of the square measure 2.5 feet. The base of the triangle is 2.5 feet and the height is 4 – 2.5 or 1.5 feet. Example 2

Area of a square Area of a triangle A = s2 A = 2.52 A = 6.25 The total area is 6.25 + 1.875 or 8.125. Answer: So, about 8.1 square feet of wood is needed for this side of the dog house. Example 2

SIDEWALK A patio is composed of a trapezoid and a rectangle SIDEWALK A patio is composed of a trapezoid and a rectangle. What is the area of the patio? A. 20 ft2 B. 56 ft2 C. 60 ft2 D. 76 ft2 Example 2 CYP

Find the Area of a Shaded Region In the figure below, two congruent triangles are cut from a rectangle. Find the area of the shaded region. Round to the nearest tenth if necessary. Find the area of the rectangle and subtract the area of the two triangles. Example 3

Find the Area of a Shaded Region Area of a rectangle A = bh A = 16 • 12 b = 16, h = 12 A = 192 Simplify. Example 3

Find the Area of a Shaded Region Area of a triangle b = 8, h = 6 Simplify. Answer: The area of the shaded region is 192 – 48 or 144 square inches. Example 3

Two triangles are cut from a square. Find the area of the shaded region. Round to the nearest tenth if necessary. A. 80 cm2 B. 90 cm2 C. 100 cm2 D. 110 cm2 Example 3 CYP