Circle Theorems 3 - The Alternate Segment Theorem
This applet investigates the Alternate Segment Theorem
Author and programmer: Ron Barrow
UK Years 10-11, Ages 14-16, KS4, Higher GCSE Mathematics - Geometry, Shape and SpaceTweet
How to Use this Applet
The line PQ is a tangent to the circle, touching the circle only once at the point A. You can move the points A, B and C around by clicking them and dragging them with your mouse. As you do so, look carefully at the size of the angles. There are different colours to help you. The sizes of the angles follow an important rule (theorem), which you can see by clicking "Show Theorem" at the bottom. Try not to do this - try to work the rule out by yourself! Enjoy yourself while you practise and learn this theorem by name.