Sample Entry

Midpoint

Formula M = ( x sub 1 plus x sub 2 all divided by 2 x₁ + x₂ 2 , y sub 1 plus y sub 2 all divided by 2 y₁ + y₂ 2 )

The x-coordinate of the midpoint is found by taking the average of the x's of the two endpoints.  The y-coordinate of the midpoint is found by taking the average of the y's of the two endpoints.

When working the midpoint formula backwards, I need to remember that I have the midpoint (M) but am missing one of the (x, y) endpoint pairs.  I also need to remember to solve for x separately. Then I solve for y.