Theorem 10.1.1

Theorem: In a parallelogram:

• The opposite sides are congruent,

• The opposite angles are congruent,

• The diagonals bisect each other.

  

Given: $||^m PQRS$

To Prove:

1. $\overline{PQ}\cong\overline{RS}$; $\overline{PS}\cong\overline{QR}$

2. $\angle{P}\cong\angle{R}$; $\angle{S}\cong\angle{Q}$

3. Diagonals $\overline{PR}$ and $\overline{SQ}$ bisect each other at point O.

Construction: In Figure (i) join point S and Q.

Proof: