# Investigating the Triangle Angle Sum Theorem

- Author:
- Ms. Benedetti, tnjcarter

**Investigating the Triangle Angle Sum Theorem**To Investigate: Click and drag the vertices of the triangle and use the sliders to rotate the vertices. Complete the activities below.

1) Hit the Reset Construction button (in upper right hand corner).
2) Click and drag the vertices to create 3 types of triangles: an acute, an obtuse, and a right triangle.
3) Record the interior angle measures of the triangle for each case.
4) Write an equation relating the 3 interior angle measures for each case.
5) Create those 3 types of triangles again, this time with the sliders (upper left hand corner) set to 180. What do you observe about the triangle's three interior angles when the sliders are set to 180?
6) Does the Triangle Angle Sum Theorem hold true for each case? Be prepared to explain your answer.