It is often used in word problems to find the distance within a function graph and then find the coordinates of a point through the distance.

It is known that the coordinates of points A and B are A(x1,y1) and B(x2,y2) respectively.

The square of the distance AB between two points is

AB²=(x1-x2)²+(y1-y2)²

Calculate and take the square root to get the distance AB.

For example: The coordinates of points A and B are known to be A(1,2) and B(4,6) respectively.

AB²=(1-4)²+(2-6)²=25

AB=√25=5

It can also be calculated directly:

AB=√[(1-4)²+(2-6)²]=√25=5