Question

Two vertices of a right triangle have the coordinates (−2, 5) and (9, 5) . What is the length of the side formed by these vertices?

Answer 1

Note that those 2 points share the same y-coordinate (5).  Thus, all you have to do is to find the distance between the x-coordinate -2 and the x-coordinate 9.  That difference is 11, and that's the desired length.