# Slopes of Perpendicular Lines 1

- Author:
- Marina Kostuch

## Perpendicular Lines

Two lines are perpendicular when they intersect at 90 degree angles.
Two lines are graphed in the plane. The slope of the first line is a/b. The slope of the second line is c/d. Change the values of a, b, c, and/or d and make note of the angle between the lines.

## Slopes of Perpendicular Lines

## Slopes of Perpendicular Lines

By examining the equations, how do you know when two lines will be perpendicular when graphed?