Lesson 6.5Parallel and Perpendicular Lines

Objective: To determine whether lines are parallel or perpendicular.

Check Skills You’ll Need

What is the reciprocal of each fraction?

1. ½

2. 4/3

3. -2/5

4. -7/5

5. 1 2/3

Check Skills You’ll Need (continue)

What are the slope and y-intercepts of each equation?

1. y = 5/3x + 42. y = 5/3 x – 83. y = 6x4. y = 6x + 25. y = -1/4x -16. y = 4x + 2

Vocabulary

Parallel lines are lines in the same plane that never intersect. Nonvertical lines are parallel if they have the same slope and different y-intercepts. Any two vertical lines are parallel.

Perpendicular lines are lines that intersect to form right angles. Two lines are perpendicular if the product of their slopes is -1. A vertical and a horizontal line are also perpendicular. The product of two numbers is -1 if one number is the negative reciprocal of the other.

Page 314

#1- 12

Writing Equations of Parallel Lines

Write an equation for the line that contains (2, -6) and is parallel to y = 3x + 9.

Page 314

#13-18

Page 314

#19 - 24

Write an Equation for Perpendicular Lines

Find an equation of the line that contains (6,2) and is perpendicular to y = -2x + 7.

Page 314

#25 - 31

Page 314

# 32 - 42

Page 314

#43 – 48 #49 – 51 #77 - 79