- Theaetetus (mathematician)
**Theaetetus**(ca. 417 B.C. – 369 B.C.) of Athens, son of Euphronius, of theAthenian deme Sunium , was a classical 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.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 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 were actually natives 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. Likewise, most Greek scientists came from the scattered Greek cities and not from Athens. Athens, and later Alexandria were centers of attraction because of the philosophical schools of Plato (the Academy) and Aristotle (the Lyceum), and the renowned Museum and Great Library. The Academy of Plato operated in Athens for almost 600 years, and served as educational center even for some of the early fathers of the Christian church.

He evidently resembled

Socrates in the snubness of his nose and bulging of his eyes. This and most of what we know of him comes fromPlato , who named a dialogue after him, the "Theaetetus". He apparently died from wounds anddysentery on his way home after fighting in anAthenian battle atCorinth , now widely presumed to have occurred in 369 BC.The Theaetetus crater on the

Moon is named after him.**External links*** [

*http://www.theaetetus.net/ A Discussion of Theaetetus' Contributions to Euclid's Elements*]

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**Theaetetus**— could mean:* Theaetetus (mathematician) (c. 417 B.C. – 369 B.C.), a Greek geometer * Theaetetus (dialogue), a dialogue by Plato, named after the geometer * Theaetetus (crater), a lunar impact crater … Wikipedia**Theaetetus**— ▪ Greek mathematician born c. 417 BC, Athens [Greece] died 369, Athens Athenian mathematician who had a significant influence on the development of Greek geometry. Theaetetus was a disciple of Socrates and studied with Theodorus of… … Universalium**Theaetetus**— (c. 414– c. 369 BC) Theaetetus was a friend of Plato s and a mathematician, who gave his name to one of the greatest of Plato s Dialogues . He is supposed to have contributed to the theory of irrationals of Euclid, Bk. x, and to the solid… … Philosophy dictionary**Nicomedes (mathematician)**— Conchoids of line with common center. Nicomedes (Νικομήδης; ca. 280 BC – ca. 210 BC) was an ancient Greek mathematician. Contents 1 Life and work … Wikipedia**Diocles (mathematician)**— Diocles (Διοκλῆς in Ancient Greek, ca. 240 BC – ca. 180 BC) was a Greek mathematician and geometer. Life and work Although little is known about the life of Diocles, it is known that he was a contemporary of Apollonius and that he flourished… … Wikipedia**Chronology of ancient Greek mathematicians**— c. 624 BC c.546 BC Thales 585 BC 525 BC Anaximenes of Miletus c. 582 BC – 507 BC Pythagoras c. 490 BC c. 420 BC Oenopides of Chios 480 BC 411 BC Antiphon the Sophist 465 BC 398 BC … Wikipedia**Greek arithmetic, geometry and harmonics: Thales to Plato**— Ian Mueller INTRODUCTION: PROCLUS’ HISTORY OF GEOMETRY In a famous passage in Book VII of the Republic starting at Socrates proposes to inquire about the studies (mathēmata) needed to train the young people who will become leaders of the ideal… … History of philosophy**mathematics**— /math euh mat iks/, n. 1. (used with a sing. v.) the systematic treatment of magnitude, relationships between figures and forms, and relations between quantities expressed symbolically. 2. (used with a sing. or pl. v.) mathematical procedures,… … Universalium**Plato: metaphysics and epistemology**— Robert Heinaman METAPHYSICS The Theory of Forms Generality is the problematic feature of the world that led to the development of Plato’s Theory of Forms and the epistemological views associated with it.1 This pervasive fact of generality appears … History of philosophy**Plato**— /play toh/, n. 1. 427 347 B.C., Greek philosopher. 2. a walled plain in the second quadrant of the face of the moon, having a dark floor: about 60 miles (96 km) in diameter. * * * orig. Aristocles born 428/427, Athens, or Aegina, Greece died… … Universalium