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
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.