Area of Parallelograms, Trapezoids and Circles Help
Area of Parallelograms, Trapezoids, and Circles
Area of a Parallelogram
The area of a parallelogram can be found by using the formula A = bh, where b is the base and h is the height or altitude .
Find the area of the parallelogram shown in Fig. 9-12 .
Area of a Trapezoid
A trapezoid has a height and two bases – a lower base, b 1 , and an upper base, b 2 (see Fig. 9-13).
The area of a trapezoid can be found by using the formula
Find the area of the trapezoid shown in Fig. 9-14 .
Area of a Circle
The area of a circle can be found by using the formula A πr 2 , where π = 3.14 and r is the radius .
Find the area of the circle shown in Fig. 9-15 . Use π 3.14.
The following suggestions will help you to convert between units. To change:
- square feet to square inches, multiply by 144;
- square inches to square feet, divide by 144;
- square yards to square feet, multiply by 9;
- square feet to square yards, divide by 9.
Change 1728 square inches to square feet.
Change 15 square yards to square feet.
Area of Parallelograms, Trapezoids and Circles Practice Problems
1. Find the area of a parallelogram whose base is 22 inches and whose height is 10 inches.
2. Find the area of a trapezoid whose bases are 32 feet and 44 feet and whose height is 20 feet.
3. Find the area of a circle whose radius is 14 inches. Use π = 3:14.
4. Find the area of a circle whose diameter is 32 feet. Use π = 3:14.
5. Change 12 square feet to square inches.
6. Change 27 square feet to square yards.
7. Change 2 square yards to square inches.
1. 220 in. 2
2. 760 ft 2
3. 615.44 in. 2
4. 803.84 ft 2
5. 1728 in. 2
6. 3 yd 2
7. 2592 in. 2
Practice problems for these concepts can be found at: Informal Geometry Practice Test.
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