Are the bases of a trapezoid always on the top and bottom? A 1 2 h (b B) A 1 2 (4 in.) a5 in. 25 3 in.b Substitute the values. A 1 2 (4 in.) a 15 3 in. 25 3 in.b Get a common denominator. A 1 2 (4 in.) a 40 3 in.b Add. A 80 3 in2 or 26 2 3 in2 Multiply. The area of the trapezoid is 80 3 in2 or 26 2 3 in2. YOU TRY 6 Find the a) perimeter and b) area of the trapezoid. 5 yd 4 yd 3 yd 6 yd 5 Find the Perimeter and Area of an Irregular Figure Sometimes, we are asked to fi nd the perimeter and area of a fi gure that consists of other fi gures put together. In this case, we must try to break down the fi gure into shapes that we know. Remember that the perimeter of a fi gure is the distance around the fi gure, while the area of a fi gure is the size of the region enclosed in the fi gure. Luciano’s garden has the shape pictured here. a) How much fencing will it take to enclose the garden? b) What is the area of the garden? Solution a) If Luciano wants to enclose the garden with a fence, 14 ft 5 ft 5 ft 16 ft 11 ft 9 ft that means the fence will go around the garden. The perimeter is the distance around a fi gure, so add up the lengths of all the sides to determine how much fencing is needed. P 14 ft 11 ft 9 ft 5 ft 5 ft 16 ft P 60 ft The perimeter is 60 ft, so Luciano needs 60 ft of fencing to enclose his garden. EXAMPLE 7 302 CHAPTER 4 Basic Geometry Concepts and Algebra www.mhhe.com/messersmith
messersmith_power_prealgebra_1e_ch4_7_10
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