1. Perpendicular Lines in the Coordinate Plane
Chapter 3 Section 3.7
Perpendicular Lines in the
Coordinate Plane

2. Warm-Up
Line m is perpendicular to line n. If line m has a positive slope, what kind of slope does line n have? A negative slope
Find the slope of the line that passes through
the points (5, 6) and (-9, 0).
(0-6)/(-9-5) = -6/-14 = 3/7

3. How Are Perpendicular Lines Related?
Postulate 18: The product of their slopes is –1.
Vertical and horizontal lines are perpendicular
Determine if the lines are perpendicular
The product of the slopes = -1, thus

4. The Slopes of Two Lines Are Given. Are They Perpendicular?
Lines are not 
Lines are 

5. Decide Whether p1 and p2 are Perpendicular
p1 is not  to p2

6. Decide Whether p1 or p2 Are Perpendicular
Yes, p1  p2