Answer:
(a/2, a/2)
Explanation:
Coordinates of B & D are; (0, a) and (a, 0) respectively.
The formula for calculating coordinates of midpoint is;
M = ((x1 + x2)/2), ((y1 + y2)/2)
Coordinates of BD will be;
M_BD = ((0 + a)/2), ((a + 0)/2)
M_BD = (a/2, a/2)