Euclidean geometry applied to Ptolemy geocentric model I'm looking for a good reference on how Ptolemy used the Euclidean geometry to calculate the planets positions.

You can always read Ptolemy himself. His " _Almagest_ ", together with the " _On the Revolutions of Heavenly Spheres_ " by Copernicus and some extracts from Kepler can be found in " _Great Books of the Western World Vol. 16_ ". Bookfinder.com lists used copies going at about $15.00 US.

Richard Fitzpatrick has prepared an excellent analysis entitled " _A Modern Almagest: An updated version of Ptolemy's Almagest_ " which can be found at <