Parallelograms

A quadrangle in which both pairs of opposite sides are parallel to each other is called a parallelogram.

The opposite sides of a parallelogram are equal in size to each other, and the opposite angles are equal - as we will show, using triangle congruence.

Other properties include:

• The diagonals of a parallelogram bisect each other
• Any two adjacent angles are supplementary

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Now that we've explained the basic concept of parallelograms in geometry, let's scroll down to work on specific geometry problems relating to this topic.