Isosceles Base Angles Congruent

Author:
schwank
Topic:
Angles
Below is a basic isosceles triangle. Manipulate the points A, B, and C by dragging the points in all directions. Make observations about what happens to the base angles at the bottom of the triangle when the points are moved.
What are the basic properties of an isosceles triangle? Does moving the points A, B, and C in blue change the fact that this is an isosceles triangle? Why or why not? What do you notice about the value of the base angles in green as the points A, B, and C are manipulated?