## Theorem of Thales Below you can see a triangle whose vertex C lies on a semicircle over segment c. Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now) Drag point C with the mouse along the semicircle and watch the angles of the triangle. Write down your observations on a sheet of paper. Judith Preiner, Created with GeoGebra