Honors Geometry Companion Book, Volume 1

3.2.4 Slopes of Parallel and Perpendicular Lines Key Objectives • Identify parallel and perpendicular lines. • Find slopes of line segments. • Write equations of parallel and perpendicular lines. Key Terms

• Parallel lines are lines in the same plane that have the same slope, and therefore never intersect. • Perpendicular lines are lines that intersect to form 90 ° angles, or right angles. The product of their slopes is − 1. Example 1 Identifying Parallel Lines To determine whether lines are parallel, compare their slopes. If the slopes are the same, then the lines are parallel.


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