Wolfram Research
Wolfram Math World: Octagon
A complex look at the octagon, which is an eight-sided polygon, from Mathworld.com.
University of Georgia
University of Georgia: Inter Math: Octagon
This site gives the general definition of a octagon with examples of regular convex and irregular concave octagons. The site has links to related terms, everyday examples, challenging problems, more information, and the interactive check...