The Theorem of Thales
In geometry, Thales' theorem states that if A, B and C are points on a circle where the line AB is a diameter of the circle, then the angle ∠ACB is a right angle. Thales' theorem is a special case of the inscribed angle theorem. This GeoGebra Applet will serve the student(s) to get to understand the concept(s) and proof for the Theorem of Thales.
Move the slider to the right to get the see the animation for the proof. You may want to move point C around the arc and get to observe the characteristics for this special type of inscribed triangle.