If you have two points [tex](x_1, y_1)[/tex] and [tex](x_2, y_2)[/tex] you can make a right angle triangle by drawing a line from [tex](x1, y1)[/tex] to [tex](x_2, y_1)[/tex] then from [tex](x_2, y_1)[/tex] to [tex](x_1, y_2)[/tex]
Now you formed a right angle triangle and can use the Pythagorean Theorem!
