Science Buddies
Science Buddies: Taking Off on a Tangent
This is an interesting geometry project that goes back to the time of Archimedes, the famous Greek mathematician. You can combine this mathematical project with computer science and take this ancient problem into the twenty-first century...
Science Buddies
Science Buddies: Thinking in (Semi )Circles: The Area of the Arbelos
The arbelos is the white-shaded region between the three semicircles in the illustration at right. In this project, you'll prove an interesting method for determining the area of the arbelos.
Wolfram Research
Wolfram Math World: Arbelos
Math World offers a detailed discussion on Arbelos and the discoveries regarding this "shoemaker's knife." The site is very detailed and some parts of the discussion may be difficult for high school students to understand.
Cut the Knot
Cut the Knot!: Interactive Mathematics: Geometry Articles, Theorems, Problems
Contains over five hundred Geometry articles, problems, puzzles, and games. Some sites relating to circles are provided within this list.