# Sum of the Interior Angles of a Quadrilateral

At the end of the lesson, students should discover that the sum of the interior angles of a quadrilateral is equal to 360 degrees.

What kind of polygon is being illustrated above?

What are the measures of the angles in each quadrilateral?

What is the sum of the interior angles of quadrilateral ABCD? quadrilateral EFGH?

You can drag the vertices of each quadrilateral. Observe what will happen to the sum of their interior angles.

What did you observe to the sum of the measures of each interior angles of the two quadrilaterals?

What can you conclude about the sum of the interior angles of a quadrilateral?