Properties of Parallelograms

Front

What is a parallelogram?

Back

A parallelogram is a quadrilateral with opposite sides that are both parallel and equal in length.

Front

What are the properties of opposite sides in a parallelogram?

Back

In a parallelogram, opposite sides are congruent (equal in length) and parallel.

Front

What can be concluded if one pair of opposite sides of a quadrilateral is both parallel and congruent?

Back

The quadrilateral is a parallelogram.

Front

What is the relationship between opposite angles in a parallelogram?

Back

Opposite angles in a parallelogram are congruent (equal in measure).

Front

What is the sum of the interior angles of a parallelogram?

Back

The sum of the interior angles of a parallelogram is 360 degrees.

Front

What can be said about the diagonals of a parallelogram?

Back

The diagonals of a parallelogram bisect each other.

Front

If two angles of a quadrilateral are congruent, what can be inferred about the opposite angles?

Back

If two angles are congruent, the opposite angles are also congruent in a parallelogram.

Front

What is the relationship between consecutive angles in a parallelogram?

Back

Consecutive angles in a parallelogram are supplementary (add up to 180 degrees).

Front

How can you prove that a quadrilateral is a parallelogram using angles?

Back

If both pairs of opposite angles are congruent, then the quadrilateral is a parallelogram.

Front

What theorem states that if one pair of opposite sides is both parallel and congruent, the quadrilateral is a parallelogram?

Back

This is known as the Converse of the Parallel Postulate.