MATHEMATICIAN

Life
Son of Euphronius of Sounion, pupil of Theodore of Cyrene, friend of Plato and member of his Academy, Theaetetus was wounded at the Battle of Corinth and died on his return to Athens. Plato dedicated one of his dialogues to him. Theaethetus, worked with Eudoxus and built on his "On means", is considered the father of stereometry. Euclid based Books X and XIII of his Elements on the work of Theaethetus.


Work
His principal works are:

"Incommensurability of the square roots of all non-square simple numbers"

"Cube roots"

"Classification of the squares of incommensurable numbers"

"On the five regular solids": Construction of the 5 regular solids (cube, pyramid, octahedron, dodecahedron and icosahedron) that can be inscribed in a circle.