Answer
$D=\sqrt {(x_2−x_1)^2+(y_2−y_1)^2}$
Work Step by Step
The distance $D$ between two points $P_1(x_1,y_1)$ and $P_2(x_2, y_2)$ can be defined by the Pythagorean theorem.
Therefore, the distance between $P_1$ and $P_2$ is given by the formula:
$D=\sqrt {(x_2−x_1)^2+(y_2−y_1)^2}$