# Quadrilateral Angle Theorems

- Author:
- John Williams, Tim Brzezinski

Interact with the applet below for a few minutes.
Then, answer the questions that follow.
Be sure to change the locations of the quadrilateral's

**BIG BLACK VERTICES**each time*before*you drag the slider!!! Note:*M*_{1, }*M*_{2, }*M*_{3, }&*M*_{4 }serve as midpoints of the sides of this quadrilateral.1) What geometric transformations took place in the applet above?

2) When working with the quadrilateral's interior angles, did any of these transformations change the measures of these interior angles?

3) From your observations, what is the sum of the measures of the interior angles of any quadrilateral?

4) When working with the quadrilateral's exterior angles, did any of these transformations change the measures of these exterior angles?

5) From your observations, what is the sum of the measures of the exterior angles of any quadrilateral?