# How do you use the vertical line test?

##### 1 Answer

Sep 30, 2014

The vertical line test is used to find out if a relation is a function.

If a vertical line is drawn for each value in the domain of a relation and if that line only intersects the relation once then the relation is a function.

**passes** the vertical line test, it is a function.

**passes** the vertical line test, it is a function.

**fails** the vertical line test, it is not a function.