# Composite Area Problems

Examples, videos, and solutions to help Grade 7 students learn how to find the area of regions in the plane with polygonal boundaries by decomposing the plane into triangles and quadrilaterals, including regions with polygonal holes.

### Lesson 20 Student Outcomes

• Students find the area of regions in the plane with polygonal boundaries by decomposing the plane into triangles and quadrilaterals, including regions with polygonal holes.
• Students find composite area of regions in the plane by decomposing the plane into familiar figures (triangles, quadrilaterals, circles, semi-circles, and quarter circles).

Lesson 20 Classwork

Example 1
Find the composite area of the shaded region. Use 3.14 for π.

Exercise 1
A yard is shown with the shaded section indicating grassy areas and the unshaded sections indicating buildings or paved areas. Find the area of the space covered with grass in units2.

Example 2
Find the area of the figure which consists of a rectangle with a semicircle on top. Use 3.14 for π.

Exercise 2
Find the area of the shaded region using π = 3.14.

Example 3
Find the area of the shaded region.

Exercise 3
Find the area of the shaded region.

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