# Reference Topics 7-1

Euclid’s Elements can be found at:
http://aleph0.clarku.edu/~djoyce/java/elements/elements.html

These sites give some great examples of symmetry.
http://www.mcescher.com/?s=symmetry

Problem 1 presents an optical illusion. If you like this sort of problem you might enjoy checking out this site.
http://www.billiardworld.com/puzzles.html

You might be interested in the art of M.C. Escher.

Three great Problems of Classical Geometry:
There are three great problems from classical geometry. The first, Squaring the Circle, the second is Doubling the Cube, and the third is Trisecting an Angle.

The first classical problem, Squaring the Circle, involves constructing a square equal in area to that of a given circle. Whether you can do this depends on the tools that you allow yourself to use. Plato was the first to attempt this construction allowing himself only a straightedge and compass.
http://mathforum.org/isaac/problems/pi3.html

The second classical problem, Doubling the Cube, involves constructing a solid with double the volume of a given solid. This site presents the problem along with many great links:
http://mathworld.wolfram.com/CubeDuplication.html
The following site gives a history of this classical problem:
https://mathshistory.st-andrews.ac.uk/HistTopics/Doubling_the_cube/

The third, and perhaps the most famous, is the classical problem of Trisection an Angle:
https://en.wikipedia.org//wiki/Angle_trisection