In the figure below, BAC is a right triangle with the excircle of radius r_a relative to the hypotenuse BC and the excircles relatives to the catheti (legs). If s is the semiperimeter and D, E, F, G, H, and M are the points of tangency, prove that r_a = s = AD = AE = BF = BH = CG = CM. View or post a solution.