Theorem: Sum of the Interior Angles of a Triangle


Grab each of the points, and move them to increase or decrease their respective angles. Pay close attention to the sum of the angles.

1. What happens when the angle size increases for each of the angles? Do the other two angles increase, decrease, or remain the same?

2. Change the size of an angle. Does the sum of all three change?

3. Is there any way to make the sum of the angles greater than 180? Less than 180? If so, how? If not, why not?