Answer:
Vertical line test to check whether relation is a function
Used by drawing a vertical line on the graph
Explanation:
Vertical line test is a test used to check whether the graph of any relation is a function or not.
In vertical line test, a vertical line will be drawn on the graph and see whether the line meets the graph at two or more points.
When a vertical line crosses the graph at two or more points then it is not a function.