# What is the slope of a line that is perpendicular to a slope of 1?

Sep 11, 2016

If ${m}_{1} = 1 , \text{ then } {m}_{2} = - 1$

#### Explanation:

A slope that is perpendicular to another slope is the negative reciprocal.

(Turn it upside down and change the sign)

If two lines are perpendicular then:

${m}_{1} \times {m}_{2} = - 1$

For ${m}_{1} = 1 = \frac{1}{1} , \rightarrow {m}_{2} = - \frac{1}{1} = - 1$