Using the Midpoint Formula A line segment has (x1, y1) as one endpoint and (xm, ym) as its midpoint. Find the other endpoint (x2, y2) of the line segment in terms of x1, y1 and ym. Then use the result to find the coordinates of the endpoint of a line segment when the coordinates of the other endpoint and midpoint are, respectively, (a) (1,-2), (4, -l) and (b) (-5, 11), (2, 4).