1. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Objectives Identify parallel lines and perpendicular lines by comparing their slopes. Write equations of lines that are parallel and perpendicular to given lines. 5.6 Parallel and Perpendicular Lines

2. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Glossary Terms parallel lines perpendicular lines 5.6 Parallel and Perpendicular Lines

3. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Rules and Properties 5.6 Parallel and Perpendicular Lines Parallel Lines If two different lines have the same slope, the lines are parallel. If two nonvertical lines are parallel, they have the same slope. Two parallel, vertical lines have undefined slopes.

4. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Rules and Properties 5.6 Parallel and Perpendicular Lines Perpendicular Lines If the slopes of two lines are m and, the lines are perpendicular. m 1 –

5. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.6 Parallel and Perpendicular Lines Recognize and write equations of lines that are parallel or perpendicular to given lines. Write an equation in slope-intercept form for the line that contains the point (0, 9) and is parallel to the line x – 5y = 4. x – 5y = 4 b = 9 slope-intercept form 1 5 4 5 y = x – 1 5 m = 1 5 y = x + 9

6. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Key Skills 5.6 Parallel and Perpendicular Lines Recognize and write equations of lines that are parallel or perpendicular to given lines. Write an equation in slope-intercept form for the line that contains the point (0, 9) and is perpendicular to the line x – 5y = 4. x – 5y = 4 b = 9 slope-intercept form 1 5 4 5 y = x – m = –5 y = –5x + 9 Negative reciprocal of : –5 1 5 TOC