At the Geometry Center.

Using the length of the three sides. The proof is better understood than the old one.

A collection of all 15 propositions from Archimedes' Book of Lemmas with complete proofs, each accompanied by a Java illustration.

History of Mathematics, very strong on geometry.

A collection of interactive geometry applets. Topics include polyhedra, Poncelet's porism, Soddy's hexlet, Mandelbrot set, Steiner porism, Pappus's chain, Repulsion polyhedra and stereo pictures.

It provides important formulations for finding a center of points in 2 or higher dimensional space. It can be used in drawing delauney triagulation and voronoi diagram in two or higher dimensions. It also describes how many points are required in defining a center in n-dimensional space.

Graffiti is a computer program that makes conjectures in mathematics and chemistry. Links to the conjectures and bibliography.

A java applet with substantial analysis related to distances on a rectangular box.

Features articles about specific problems, illusions, and puzzles. Includes diagrams.

By Clark Kimberling. Over 1000 triangle centres in a searchable compilation with diagrams.

Graphics and links for various packing, tiling and covering problems.

Free online book on geometry in pdf format. Contains material not easily found elsewhere from detailed exposition of elementary absolute geometry based on Hilbert's axioms to more advanced topics.

Information and resources about geometric group theory and low-dimensional topology. People, groups, meetings, links.

By Ephraim Fithian.

Geometry exercises for a two-week summer workshop led by John Conway, Peter Doyle, Jane Gilman and Bill Thurston at the Geometry Center in Minneapolis, June 1991.

Web site for the (now closed) Center for the Computation and Visualization of Geometric Structures at the University of Minnesota. Graphics, multimedia, software, teaching resources.

Excerpts from the 30th Edition of the CRC Standard Mathematical Tables and Formulas (1995), namely, the geometry section minus differential geometry.

Presents problems involving circles and triangles, with proofs, SAT practice quizzes and famous quotes. Also, has examples of geometry in Peruvian culture.

Includes collections from various areas in which ideas from discrete and computational geometry meet real world applications.

Includes articles on topics in elementary and not so elementary geometry, many with interactive Java illustrations and multiple proofs.

A new type of geometric construction that was discovered by Dan Litchfield and David Goldenheim. Includes general explanation and sketch examples.

Course notes by Bill Cherowitzo.

Search the Geometry Problem of the Week's archive of creative, non-routine challenges, as well as submissions and commentary, dating back to 1993.

Discussion board for geometry professors and instructors to keep informed of the latest research.

Those interested in examining the previous incarnation of the Math Forum may search the archives of the Geometry Forum.