Download - Lesson 2-2-3
Lesson 2-2-3-Determine if lines are
parallel, perpendicular, or neither
Parallel/Perpendicular
Comparing slopes of lines can help determine if two lines are parallel, perpendicular, or neither.
Two lines are parallelparallel if they have the same slopes (and different y-
intercepts)
Two lines are perpendicularperpendicular if their slopes are opposite reciprocals
Examples:Determine if the lines are parallel,
perpendicular, or neither.
1) and 4x – y = -1 47
x41
y
Examples:Determine if the lines are parallel,
perpendicular, or neither.
2) the line passing through (1, 6) and (8, -1) and x + y = 2
Examples:3) Write an equation in Slope-Intercept form
of the line passing through the point (5, -3) and perpendicular to the line y = 4x + 1
Examples:4) Write an equation in standard form of the
line passing through (2, 1) and parallel to the line
85
x32
y
Wrap-Up:
How can you use the equations of two non-vertical lines to tell whether the lines are parallel or perpendicular?
Find the slopes and compare:--Same slope – parallel
--Opposite reciprocal slopes - perpendicular
Assignment:
Practice 6-5 worksheet