what is the relationship between the area of a parallelogram and the area of a trapezoid?
The two parallel sides are the bases, and height, as always, is the perpendicular distance from one base to the opposite. See trapezoid. The area of this parallelogram is its height (half-height of the trapezoid) times its base (sum of the bases of the trapezoid), so its area is half-height x (base1 + base2).