# The slope of a line is m. What is the slope of a line perpendicular to this line?

We will use the concept of straight lines in order to find the slope of another perpendicular line.

## Answer: -1 / m is the slope of a line perpendicular to a line with a slope of m.

Let us see how we will use the concept of straight lines in order to find the slope of another perpendicular line.

**Explanation:**

It is given that the slope of one line is m.

We also know that the product of slopes of two perpendicular lines is always -1.

Let us consider the slope of another perpendicular line is n.

Hence, m × n = -1

⇒ n = -1/m