**1. Vertical line test**

Vertical line test is a visual way of determining that the given relation is a function or not. If the vertical line drawn intersects the graph of the relation at more than one point then the given relation is not a function. If it intersect at one point then it is a function. With the vertical line test we check the one to one relation. A function can have only one y value for each unique value of ‘x’.

**2. Interactive Graph**

Use the interactive graph given below to draw the graph of any relations, press the play button and using vertical line test determine that the relation is a function or not.

**3. Interactive Graph**

Use the interactive graph given below to draw the graph of any relations. Use the input box to enter any relation and use the start and reset buttons to animate the vertical line and using vertical line test determine that the relation is a function or not.