WARM UP

RATIOS Convert the units. (Lesson 3.8)

1. 5 days to hours

2. 36 inches to feet

3. 12 years to months

3

WARM UP

RATIOS Convert the units. (Lesson 3.8)

1. 5 days to hours

2. 36 inches to feet

3. 12 years to months

2

WARM UP

RATIOS Convert the units. (Lesson 3.8)

1. 5 days to hours

2. 36 inches to feet

3. 12 years to months

1

RATIOS Convert the units. (Lesson 3.8)

1. 5 days to hours

2. 36 inches to feet

3. 12 years to months

WARM UP 0

5.6 Perpendicular Lines

GOALWrite equations of perpendicular lines.

KEY WORDSPerpendicular

5.6 Perpendicular Lines

PERPENDICULARQUESTION: What is the definition of this word?

Lines that intersect at a RIGHT, or 90⁰, angle are called perpendicular.

90⁰ angle

5.6 Perpendicular Lines

EXPLORE1. This line has a slope

of . Copy the line onto a piece of graph paper.

m = 3

4

5.6 Perpendicular Lines

EXPLORE2. Draw a line on the graph paper that is perpendicular to the first line.

5.6 Perpendicular Lines

EXPLORE3. Find the slope of the

perpendicular line using m = .

m =

-4

3

5.6 Perpendicular Lines

EXPLORE4. Find the product of

the slopes of the two lines.

• = = -1

5.6 Perpendicular Lines

In a coordinate plane, two nonvertical lines are perpendicular if and only if the product of their slopes is -1.

y = x

y = -2x + 3

• -2 = -1

5.6 Perpendicular Lines

Horizontal and vertical lines are perpendicular to each other.

y = 6

x = 3

5.6 Perpendicular Lines

EXAMPLE 1 IDENTIFY PERPENDICULAR LINESDetermine whether the lines are perpendicular.SOLUTIONThe lines have slopes of and -3. Because • -3 = -1, The lines are perpendicular.

y = x -1

y = -3x + 4

5.6 Perpendicular Lines

CHECK POINT

Graph and determine whether the lines are perpendicular.1. y = 3x + 2, y = -3x -1

2. y = x + 1, y = - x + 1

#1: NOT PERPENDICULAR!#2: PERPENDICULAR!

CERTIFIED

5.6 Perpendicular Lines

Page 309 #1 and 2Graph and determine whether the lines are perpendicular for #’s 3-6 and 11 - 16

CLASSWORK