Who is Theodorus of Cyrene?

Answer 1

Theodorus of Cyrene was born in Cyrene and spent most of his life in Athens, Greece. He was a Greek mathematician of the 5th century BC who was admired by Plato (who mentions him in several of his works). Little is known about him; however, Plato attributes to him the first proof of the irrationality of the square roots of 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15 and 17. The method he used is not stated, but since he stopped at 17, it seems possible that he used the traditional Pythagorean method of odds and evens, since 17 is the first number for which this method breaks down.