Properties of Parallelograms

A parallelogram is a Quadrilateral with both pairs of opposite sides parallel.

Properties

• Opposite sides are congruent.
• Opposite angles are congruent.
• Consecutive angles are supplementary (sum to 180°).
• Diagonals bisect each other.

Using Properties

If ABCD is a parallelogram:

• AB ∥ CD and AD ∥ BC (definition)
• AB = CD and AD = BC (opposite sides congruent)
• ∠A = ∠C and ∠B = ∠D (opposite angles congruent)
• ∠A + ∠B = 180° (consecutive angles supplementary)
• Diagonals AC and BD bisect each other at Point M (AM = MC, BM = MD)