# What is the slope of a line that is parallel to a vertical line?

##### 2 Answers

Any line that is parallel to a vertical line is also vertical and has undefined slope.

#### Explanation:

A vertical line is given by the equation

Its slope

which is undefined.

A vertical line and all lines parallel to it have undefined slopes

#### Explanation:

Note that if a line is vertical, all lines parallel to it are also vertical.

For any two points

the slope is defined as

BUT if the line is vertical

and therefore the definition of the slope would require dividing by zero (which is undefined).