Chapter 4.1, Problem 30E

In Exercises 27-30, use the definition of a parallelogram to complete each proof.

Given: Parallelogram ABCD with $\stackrel{-}{DE}\perp \stackrel{-}{AB}$ and $\stackrel{-}{FB} \perp \stackrel{-}{AB}$

Prove: $\stackrel{-}{DE}\cong \stackrel{-}{FB}$

Plan: First show that DEBF is a parallelogram.