Elementary Geometry
by Ilka Agricola and Thomas Friedrich

Here is a collection of links related to topics in our book - guaranteed to be subjective, incomplete and time consuming. Any hints or comments are highly welcome. Enjoy!
Geometry section of "Math World" - a universal geometry resource by Eric Weisstein at Wolfram Research
Geometry section of "Math Pages" - another collection of interesting pages

Mathematical Craftwork
A collection of `mathematical craftwork' pages
(left column is in English) - includes paper foldings, caleidocycles, cube puzzles, polyhexes, Platonic solids etc.
Craft Technology Research Group
(University of Colorado at Boulder) - using modern technology for hands-on paper folding (`JavaGami'), pop-ups etc.
Card Board sheets
for easy made polyhedra (most easily ordered from inside Germany, though)
Zome Tool
- the easiest kit around for building plastic models (see also the book Zome Geometry by G. Hart and H. Picciotto)

Mathematical & Mechanical Puzzles
Puzzle World
a page maintained by John Rausch - includes literature, links to manufacturers etc.
The Puzzling World of Polyhedral Dissections
- the ultimate book on the topic by Stewart T. Coffin

The encyclopedia of polyhedra
THE online reference by artist George W. Hart (includes an impressive annotated bibliography and some classroom ideas)
Geodesic domes
as well as two pages about their mathematics by Dave Anderson and Rene Mueller, and an origami version
Euler's polyhedron formula as a starting point for modern polytope theory
by Christian Blatter and Günter Ziegler, published in Elem. Math. 62 (2007), 184-192.

Tilings & their relatives
What symmetry groups are present in the Alhambra?
by Branko Grünbaum, published in the Notices of the AMS, June/July 2006
The Grammar of Ornament
Digitalized version of Owen Jones's holy grail of art reference books (first published 1856)
Introduction to quasicrystals
by Steffen Weber
From quasicrystals to Kleenex
an introduction to aperiodic tilings by Alison Boyle, published in + plus magazine, September 2001

Geometric figures (triangles, circles, lines etc.)
Encyclopedia of triangle centers
together with illustrations for it and the connection to the Euler line by Clark Kimberling
Geometry in Action
java animated visualisations of geometric properties & constructions by Clark Kimberling
The Shape and History of The Ellipse in Washington, D. C. by Clark Kimberling The Theorems of Steiner and Poncelet
An animated introduction to the porisms of Steiner and Poncelet on circle chains and related topics by Thomas Bauer
Ceva, Menelaus and the Area Principle
A generalisation of the theorems of Ceva and Menelaos to planar polygons by Branko Grünbaum and Geoffrey C. Shepard, published in Mathematics Magazine 68 (1995), 254-268
Ruler and compass constructions
Illustrations using JavaSketchpad ranging from drawing a parallel to constructing a 17-gon by Ken Brakke

Other Symmetries
Alice through looking glass after looking glass: The Mathematics of Mirrors and Kaleidoscopes
by Roe Goodman, published in The American Mathematical Monthly, April 2004
The graph of the truncated icosahedron and the last letter of Galois
by Bertram Kostant, published in the Notices of the AMS, September 1995

Questions and comments concerning this page should be addressed per e-mail to

Ilka Agricola / 14.02.2008