A theorem is illustrated in the simulation below
A circle is drawn with two angles marked. The central angle CAD and angle at the circumference angle CED Click the play button and Observe it carefully. You can move the points in the circle. Also you can increase or decrease the size of the circle by clicking on the Radius Changer point and zooming it in and out.
Based on your observation try to answer this question
What is the relationship between <CAD and <CED
From the above simulation you find that the central angle is double the angle at the circumference
This illustrates the Theorem