The proportion of a inscribed and a central angles.
This applet shows why an inscribed angle and a central angle are related by a proportion of 1:2
Drag point G around, and verify that gamma angle's size is the double of alphas' size.
- Why do you think this is always the case?
- alpha and gamma are actually just parts of the inscribed and central angles in the applet. Why is it true that the same relationship between alpha and gamma holds for the inscribed and central angles?