Geometry Problems and Puzzles

This page contains a motely collection of problems and puzzles of elementary geometry that at one point or another have intrigued and amused me. I hope that you will enjoy them as much as I have.

Wherever possible, I have used David Joyce's wonderful Geometry Applet to produce interactive illustrations and diagrams. You will need a java-enabled browser to see the drawings.

List of problems and puzzles

The asymmetric_propeller

A theorem popularized by Martin Gardner in an article in The College Journal of Mathematics.

An inequality concerning equilateral triangles

This may be known as the Van Schooten Theorem. The elegant solution given here is due to Dan Hoey.

The maximal angle problem

On how to get the widest angle of view.

Another problem concerning equilateral triangles

Intriguing puzzle proposed by Steve Gray.

Common tangents of two circles

A relationship between the common tangents of two circles.

Angle trisection

• Trisection proposed by Mark Stark
• Alternative trisection proposed by Mark Stark
• Trisection proposed by C. R. Lindberg and Free Jamison
• A more accurate trisection proposed by Free Jamison
• A trisection from Trisectors by Dudley Underwood

This page created and maintained by Rouben Rostamian