This is COO - EL

Computer Observations Of Euclid

by Paul Godfrey

This is the beginning in a series of expositions based on Euclid using the Geometer's Sketchpad as an illustrator. It relies on the famous translation work of John Playfair.

Part I begins with the definitions propounded by Euclid. I have provided for interactive viewing which requires at least a demonstration copy of Geometer's Sketchpad 3.0. You can obtain the demo version from Key Curriculum press in either 'Macintosh' or 'Windows' versions.


To begin this journey, please select



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  1. John Playfair, Elements of Geometry: The First Six Books of Euclid with a Supplement on the Quadrature of the Circle and the Geometry of Solids, W.E.,Dean, Printer and Publisher, 2 Ann Street, New York, New York, 1849.
  2. "Geometer's Sketchpad", Key Curriculum Press,