An isosceles trapezoidal lot ABCD has an altitude of 80 m. and sides BC parallel to AD. The area of the lot is 5000 2 . a) If the two bases have the ratio of 3:7, compute the perimeter of the lot; b) Compute the dividing line if the trapezoidal lot is divided into parts in the ratio of 1 to 3 by a line parallel to sides BC and AD, and c) Find the area of the largest part.