Find the area of each triangle. a) b) 8 cm 10 cm 21 cm 17 cm 1 ft 5 8 ft 5 8 1 ft 1 2 c) 25 in. 18 in. 7 in. Solution a) Identify the base, b, and height, h. Remember, the base is the side that forms the right angle with the height. b 21 cm h 8 cm (We do not need the lengths 17 cm and 10 cm.) A 1 2 bh A 1 21 4 cm) Substitute the values, and divide out 2. (21 cm)(8 A 84 cm2 Multiply. The area is 84 cm2. Remember to use square units for area. b) Identify the base, b, and height, h: b 1 1 2 ft, h 5 8 ft A 1 2 bh A 1 2 a1 1 2 ftb a 5 8 ftb Substitute the values. A 1 2 a 3 2 ftb a 5 8 ftb Change the mixed number to a fraction. A 15 32 ft2 Multiply. The area is 15 32 ft2. c) In this triangle, the base must be extended with a dotted line to fi nd the height. (The base is still the base of the actual triangle.) Identify the base, b, and the height, h: b 18 in. and h 7 in. A 1 2 bh A 1 2 (18 in.)(7 in.) Substitute the values. A 63 in2 Multiply. The area is 63 in2. EXAMPLE 2 Remember, the best way to read a math book is to write out the example as you are reading it. 310 CHAPTER 4 Basic Geometry Concepts and Algebra www.mhhe.com/messersmith
messersmith_power_prealgebra_1e_ch4_7_10
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