Inscribed Angle on a Semicircle (Thales' Theorem)

This GeoGebra applet demonstrates Thales' theorem: any angle inscribed in a semicircle is always a right angle. The construction features a circle with a diameter as the base, and a movable point on the semicircular arc forming a triangle. As users drag the point along the arc, they can observe that the inscribed angle remains exactly 90° regardless of the point's position. The applet illustrates