## College Algebra (10th Edition)

$d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$
The distance between two points can be modeled with the Pythagorean theorem. Thus, the distance between $P_1$ and $P_2$ would be: $d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$