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Perimeter Perimeter is defined as the distance around an object. For a polygon (an object with many sides) the perimeter is the sum of the lengths of the sides. For a circle the distance around the outside is called the circumference. Rectangle P = 2l + 2w Square Triangle P = 4s P=a+b+c Circle Circumference: C = 2r or C = d Example 1: Finding Perimeter and Circumference Find the perimeter or circumference as indicated. Use 3.14 for . a. Perimeter: b. Perimeter: Solution: a. P=a+b+c Add the lengths of the sides P = 4 in. + 2 in. + 5 in. = 11 in The perimeter is 11 inches b. P = 2 l + 2w Substitute l = 5.5 ft and w = 3.1 ft P = 2(5.5 ft) + 2(3.1 ft) = 11 ft + 6.2 ft = 17.2 ft The perimeter is 17.2 feet c. C = 2r Substitute r = 6 cm and leave in your answer C = 2()(6 cm) = 12 cm The circumference is 12 cm The Academic Support Center at Daytona State College (Math 55 pg 1 of 1) c. Circumference