Consider the paragraph proof. Given: d is the midpoint of ab, and e is the midpoint of ac. Prove:de = bc it is given that d is the midpoint of ab and e is the midpoint of ac. To prove that de is half the length of bc, the distance formula, d = , can be used to determine the lengths of the two segments. The length of bc can be determined with the equation bc = , which simplifies to 2a. The length of de can be determined with the equation de = , which simplifies to . Therefore, bc is twice de, and de is half bc. Which is the missing information in the proof? a 4a a2 4a2.