Sixth circle theorem

First page
Theorem 1
Theorem 2
Theorem 3
Theorem 4
Theorem 5
Theorem 6
Theorem 7
The Seven Theorems

Angle between tangent and radius

Sixth circle theorem:

What do you notice about the angle between tangent and radius, α & β?

You can use the cursor to move point C, and you can change the size of the circle by moving point A or B.

This is a Java Applet created using GeoGebra from - it looks like you don't have Java installed, please go to

If you need them, the seven circle theorems here

Tim Devereux, Created with GeoGebra