Formula Perimeter of a Square s s s s The perimeter, P, of a square with side length s can be found using one of these formulas: Perimeter side side side side or P 4 side or P 4s We fi nd the area of a square by multiplying length times width, but since those values are the same, we can use one of the following formulas. Formula Area of a Square s s The area, A, of a square with side length s can be found using one of these formulas: Area side side or A s s or A s2 The units for area are square units. EXAMPLE 4 7 cm For the square pictured here, fi nd a) its perimeter and b) its area. Solution 7 cm a) Identify the side length, s: s 7 cm Use the formula P 4s or add up all the side lengths. Formula Add side lengths P 4s P side side side side P 4(7 cm) P 7 cm 7 cm 7 cm 7 cm P 28 cm P 28 cm The perimeter is 28 cm. We get the same result using either method. b) The side length is s 7 cm. Use one of the formulas to fi nd the area. A side side or A s2 A (7 cm) (7 cm) A (7 cm)2 A 49 cm2 A 49 cm2 The area is 49 cm2, and we get the same answer using either formula. YOU TRY 4 For the square pictured here, fi nd 3 ft 4 3 ft 4 a) its perimeter and b) its area. 298 CHAPTER 4 Basic Geometry Concepts and Algebra www.mhhe.com/messersmith
messersmith_power_prealgebra_1e_ch4_7_10
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