Ptolemy

Claudius Ptolemy, better known as Ptolemy, was a Greco-Roman writer of the second century AD who lived in or around Alexandria in the Roman province of Egypt and wrote about a dozen scientific treatises. Three were important to later Byzantine, Islamic and Western European science: the astronomical Almagest, originally titled Mathematical Treatise, the Geography, a discussion of maps and the geographic knowledge of the Greco-Roman world, and the astrological Tetrabiblos. His Almagest set out the only mathematically sound geocentric model of the Solar System and was widely copied, though few mastered the mathematics needed to follow it. Ptolemy theorem on distances in a cyclic quadrilateral bears his name.