Theaetetus of Athens ( / ˌ θ iː ɪ ˈ t iː t ə s / ; ‹See Tfd› Greek : Θεαίτητος Theaítētos ; c. 417 – c. 369 BCE), possibly the son of Euphronius of the Athenian deme Sunium , was a Greek mathematician. His principal contributions were on irrational lengths, which was included in Book X of Euclid's Elements and proving that there are precisely five regular convex polyhedra . A friend of Socrates and Plato , he is the central character in Plato's eponymous Socratic dialogue .
6-539: Theaetetus (Θεαίτητος) is a Greek name which may refer to: Theaetetus (mathematician) (c. 417 BC – 369 BC), Greek geometer Theaetetus (dialogue) , a dialogue by Plato, named after the geometer Theaetetus (crater) , a lunar impact crater Theaetetus (poet) (fl. 3rd century BC), Greek poet Theaetetus of Cyrene (Θεαίτητος ὁ Κυρηναῖος) (fl. 270 BC), Greek poet Theaetetus Scholasticus (Θεαίτητος ὁ σχολαστικός) (fl. 6th century AD), Greek poet Topics referred to by
12-663: Is different from Wikidata All article disambiguation pages All disambiguation pages Theaetetus (mathematician) Theaetetus, like Plato, was a student of the Greek mathematician Theodorus of Cyrene . Cyrene was a prosperous Greek colony on the coast of North Africa, in what is now Libya, on the eastern end of the Gulf of Sidra . Theodorus had explored the theory of incommensurable quantities, and Theaetetus continued those studies with great enthusiasm; specifically, he classified various forms of irrational numbers according to
18-482: The Moon is named after him. Thesleff, Holger (1989). "Platonic Chronology". Phronesis . 34 (1): 1–26. doi : 10.1163/156852889X00017 . p. 18, footnote 67: I find it essential to note that the historians of mathematics who take for granted that Theaitetos was still active in the 370s must be wrong. He made some important discoveries as a young man, and Plato and his friends were deeply impressed by this. But he
24-456: The same term [REDACTED] This disambiguation page lists articles associated with the title Theaetetus . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Theaetetus&oldid=1194651012 " Categories : Disambiguation pages Human name disambiguation pages Hidden categories: Short description
30-507: The snubness of his nose and bulging of his eyes. This and most of what is known of him comes from Plato, who named a dialogue after him, the Theaetetus . He apparently died from wounds and dysentery on his way home after fighting in an Athenian battle at Corinth , now presumed to have occurred in 369 BC; some scholars argue alternately for 391 BC as his date of death, the date of an earlier battle at Corinth. The crater Theaetetus on
36-571: The way they are expressed as square roots. This theory is presented in great detail in Book X of Euclid's Elements . Theaetetus was one of the few Greek mathematicians who was actually a native of Athens. Most Greek mathematicians of antiquity came from the numerous Greek cities scattered around the Ionian coast, the Black Sea and the whole Mediterranean basin. He evidently resembled Socrates in
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