Definition/Procedure Example Identifying Parallel and Perpendicular Lines Two lines that cross each other are called intersecting lines. Parallel lines are lines in the same plane that do not intersect. The symbol 7 means “is parallel to.” Perpendicular lines intersect at right angles. The symbol means “is perpendicular to.” (p. 289) Classify each pair of lines as parallel, perpendicular, or neither. If they are parallel or perpendicular, use the appropriate notation. a) J W X K b) b a c) M P N O Solution a) Lines JK · · and WX meet at right angles, so they · are perpendicular. Write JK · . WX b) Lines a and b do not intersect, so they are parallel. Write a 7 b. · c) Lines MN · and OP intersect but not at right angles. They are neither parallel nor perpendicular. 4.2 Rectangles, Squares, Parallelograms, and Trapezoids Rectangles A rectangle is a four-sided fi gure containing four right angles. The opposite sides are parallel and congruent. The longer side of a rectangle is called the length, l. The shorter side is called the width, w. A small square indicates that the rectangle has four 90 angles. (p. 294) Perimeter of a Rectangle The perimeter of a fi gure is the distance around the fi gure. We can fi nd the perimeter, P, of a rectangle using one of the following formulas: 1) P 2 length 2 width or 2) P 2l 2w (p. 294) width, w length, l Find the perimeter of the rectangle. 7 cm 3 cm P 2l 2w P 2(7 cm) 2(3 cm) Substitute the values. P 14 cm 6 cm Multiply. P 20 cm Add. 344 CHAPTER 4 Basic Geometry Concepts and Algebra www.mhhe.com/messersmith
messersmith_power_prealgebra_1e_ch4_7_10
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