Math 150

Theorems about Parallelograms

Dr. Wilson

Theorem 6: A parallelogram is a rectangle if and only if the diagonals are the same length.

Since this is an "if and only if" proof, there are two things to prove.

1. Given: ABCD is a rectangle.

To prove: AC = BD

and the converse

2. Given: ABCD is a parallelogram, AC = BD

To prove: ABCD is a rectangle.