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Unformatted text preview: ula may be used for a square if the diagonal is given. The diagonals of a square are equal. Area = 1 (8)(8) = 32 2 Remember also that a rhombus is not a square. Therefore do not use the s2 formula for a rhombus. A rhombus, however, is a parallelogram, so you may use bh if you do not know the diagonals. E. Triangle = 1 2 · base · altitude = 1 bh 2 A= 1 (8)(3) = 12 2 F. Equilateral Triangle = 1 4 · side squared · 3= s2 3 4 A= 36 3=9 3 4 G. Trapezoid = 1 2 · altitude · sum of bases = 1 h ( b1 + b2 ) 2 A= 1 (3)(14) = 21 2 www.petersons.com Geometry 201 H. Circle = π · radius squared = π · r2 A = π · (5)2 = 25π Remember that π is the ratio of the circumference of any circle and its diameter. π = d . The approximations 22 you have used for π in the past (3.14 or ) are just that—approximations. π is an irrational number and cannot 7 be expressed as a fraction or terminating decimal. Therefore all answers involving π should be left in terms of π unless you are given a specific value to substitute for π. A word about units—Area is measured in square units. That is, we wish to compute how many squares one inch on each side (a square inch) or one foot on each side (a square foot), etc., can be used to cover a given surface. To change from square inches to square feet or square yards, remember that
144 square inches = 1 square foot 9 square feet = 1 square yard c 12" = 1' 12 one inch squares in a row 12 rows 144 square inches in 1 sq. ft. 3' = 1 yd. 3 one foot squares in a row 3 rows 9 square feet in 1 sq. yd. www.petersons.com 202 Chapter 13 Exercise 1
Work out each problem. Circle the letter that appears before your answer. 1. The dimensions of a rectangular living room are 18 feet by 20 feet. How many square yards of carpeting are needed to cover the floor? (A) 360 (B) 42 (C) 40 (D) 240 (E) 90 In a parallelogram whose area is 15, the base is represented by x + 7 and the altitude is x – 7. Find the base of the parallelogram. (A) 8 (B) 15 (C) 1 (D) 34 (E) 5 The sides of a right triang...
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This note was uploaded on 08/15/2010 for the course MATH a4d4 taught by Professor Colon during the Spring '10 term at Embry-Riddle FL/AZ.
- Spring '10