# Convex and Concave Quadrilaterals-What's the difference?

In this video you will learn the difference between a convex quadrilateral and a concave quadrilateral.

A quadrilateral is a four sided polygon.

Quadrilaterals come in different shapes and sizes, and many common shapes we encounter daily are quadrilaterals.
A few examples would be a square, rectangle, parallelogram, rhombus, and a kite.

Quadrilaterals can be further divided by the interior angle measurements.

A convex quadrilateral have interior angles 180 degrees or less, a concave quadrilateral has an interior angle measure greater than 180 degrees.
Most common quadrilaterals are convex, and  they do not have any interior angle measure
greater than 180 degrees.
A concave quadrilateral has a reflex interior angle measure. In other words one interior angle measure is greater than 180 degrees.
A dart is one example of a concave quadrilateral.

A helpful method for memorizing the difference between these two types of quadrilaterals
is to think of a cave for a concave quadrilateral. The reflex angle creates a cavity of
a cave, which has an angle measure greater than 180 degrees.