Question

The midpoint of CD is M=(5. –1). One endpoint is C=(7.1).

Find the coordinates of the other endpoint, D.

Answer 1

D = (3, -3)

Explanation:

A key fact needed to solve this is that the distance of C to M is equal to the distance of D to M, as M is the midpoint of CD. Now considering the x and y distance of C to M separately, C is 2 to the right (7 - 5) and 2 up from (1 - -1) M. This means that, conversely, D has to be 2 to the left and 2 down from M. Doing the maths, we see that (5 - 2, -1 - 2) = (3, -3).