The midpoint
(x,y) and the end point
(22, y2) are known. Find
(21, y1) using the midpoint formula.


(21, y1) = (x + 22, y + y2)
(21, yı) = (2x – 22, 2y - y2)
(21, y1) = (x – 22, y - y2)
(21, yı) = (2x + 22,2y + y2)