Thales Theorem
1. Draw a line segment AB.
2. Draw a semicircle through points A and B then another semicircle through points B and A.
3. Now, we have the diameter of the circle, line segment AB.
4. Plot any point on the circumference of the circle and label the point C.
5. Create a triangle ACB.
6. Find the angle measure of each angle. Drag point C along the semicircle and that angle C will always be a right angle.