# Thale's Theorem 1

- Author:
- Ken Garrabrant

Objective: I will be able to show and explain why a triangle inscribed in a circle when one side is the diameter of the circle is a right triangle.

1. A right triangle has two legs and a hypotenuse. Which of the sides of the triangle is the hypotenuse?
2. With regard to the hypotenuse, by what other name would it be called in the circle.
3. <CED is an inscribed angle. What is the name and measure of the arc intercepted by <CED?
4. Given that information, explain why <CED has to be a right angle?
5. Drag Point E to several places around the circle. Explain why the measure of <CED does not change.
6. When you drag Point E to the bottom of the circle, the angle says its 270, explain why Triangle CED is still a right triangle.