n Learning and Teaching Mathematics - Deriving the composite angle formulae for sine from Ptolemy

Volume 2012, Issue 13
  • ISSN : 1990-6811


Ptolemy of Alexandria (approximately 100-168 AD) not only developed his Planetary theory in his treatise , but also proved the following remarkable theorem, known as Ptolemy's theorem, which he used to compute his table of chords (trigonometric tables) that was in use for over 1000 years: "The sum of the two products of the opposite sides of a cyclic quadrilateral is equal to the product of the diagonals; e.g. + = ."

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