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5.8 Slope of Parallel and Perpendicular Lines
ALGEBRA 5.8
Language Goal• Students will be able to Identify and graph
parallel and perpendicular lines.Math Goal• Students will be able to write equations to
describe lines parallel or perpendicular to a given line.
Essential Question• How can you find a parallel line or
perpendicular line?
LEARNING TARGETS
WARM-UP
HOMEWORK CHECK
HOMEWORK CHECK
HOMEWORK CHECK
DISCOVERY
Draw an xy-axis on your graph paper.
Plot the point (0, 0)
Create one line by having a slope of .
Plot the point (0,2)Create another line by having a slope of
What do you notice about the two lines?
What do we call these lines?
GRAPH
DISCOVERY
Draw an xy-axis on your graph paper. Plot the point (0, 0)
Create one line by having a slope of 2.
Create another line by having a slope of
What kind of angle do the two lines form?
What do we call these lines?
GRAPH
Parallel
Perpendicular
VOCABULARY
Lines that have no points in common.
They never intersect.
Lines that intersect to form right angles, 90°
Parallel lines have the same slope.
Perpendicular lines have opposite reciprocal slopes.
opposite reciprocals
OVERVIEW
Parallel lines horizontal lines are parallel vertical lines are parallel.
Perpendicular lines
vertical and horizontal lines are perpendicular
OVERVIEW
Identify which lines are parallel. Find the slope of each line first!
A.
EXAMPLE 1: IDENTIFYING PARALLEL LINES
Identify which lines are parallel.
B.
EXAMPLE 1: IDENTIFYING PARALLEL LINES
Identify which lines are parallel.
C.
EXAMPLE 1: IDENTIFYING PARALLEL LINES
Identify which lines are parallel.
D.
EXAMPLE 1: IDENTIFYING PARALLEL LINES
Identify which lines are perpendicular.
A. x = -2; y = 1; y = -4x; y + 2 = (x + 1)
EXAMPLE 3: IDENTIFYING PERPENDICULAR LINES
Identify which lines are perpendicular.
B. y = -4; y – 6 = 5(x + 4); x = 3; y = x + 2
EXAMPLE 3: IDENTIFYING PERPENDICULAR LINES
Identify which lines are perpendicular.
C.
EXAMPLE 3: IDENTIFYING PERPENDICULAR LINES
A. Write an equation in slope-intercept form for the lie that passes through (4, 5), and is parallel to the line described by y = 5x + 10.
EXAMPLE 5:WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR
LINES
B. Write an equation in slope-intercept form for the line that passes through (3, 2), and is perpendicular to the line described by y = 3x – 1.
EXAMPLE 5:WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR
LINES
C. Write an equation in slope intercept form for the line that passes through (5, 7), and is parallel to the line described by y = x – 6
EXAMPLE 5:WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR
LINES
D. Write an equation in slope-intercept form for the lien that passes through (-5, 3) and is perpendicular to the lien described by y = 5x.
EXAMPLE 5:WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR
LINES
E. Write an equation in slope-intercept form for the line that passes through (4, 10) and is parallel to the line described by y = 3x + 8.
EXAMPLE 5:WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR
LINES
F. Write an equation in slope-intercept form for the line that passes through (2, -2) and is perpendicular to the lien described by y = 2x – 5.
EXAMPLE 5:WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR
LINES
LESSON QUIZ
