In trapezoid ABCD, E and F are the midpoints of AB = 20, DC = 28, and (a) Find x and y.(b)...

In trapezoid ABCD, E and F are the midpoints of AB = 20, DC = 28, and

(a) Find x and y.

(b) Find the length of the median .

(c) Is your answer for EF the average of AB and DC? Try to prove this relation for any trapezoid using this method. (Compare with the above proof given for Theorem 2.)