Solution: Let the trapezoid have bases of lengths $ a = 120 $ m and $ b = 180 $ m, and equal legs of length $ l = 50 $ m. The height $ h $ can be found by dropping perpendiculars from the ends of the shorter base to the longer base, forming two right triangles on either side and a rectangle in the middle. The difference in the bases is $ b - a = 60 $ m, so each of the right triangles has a base of $ \frac602 = 30 $ m. Using the Pythagorean theorem: - Groen Casting