Theorem 14.1.2

Theorem: Parallelograms on equal bases and having the same altitude are equal in area.

Given: Parallelogram ABCD and EFGH are on equal bases $\overline{BC}$ and $\overline{FG},$ having equal altitudes.

To Prove:

$▰ ABCD = ▰ EFGH$.

Construction:

Place the parallelograms ABCD and EFGH so that their equal base $\overline{BC}$ and $\overline{FG}$ are on the same straight line. Join B to E and C to H.

Proof: