Theaetetus

▪ Greek mathematicianborn c. 417 BC, Athens [Greece]died 369, AthensAthenian mathematician who had a significant influence on the development of Greek geometry.Theaetetus was a disciple of Socrates and studied with Theodorus of Cyrene. He taught at some time in Heraclea (located in presentday southern Italy). Plato made Theaetetus the chief subject of two dialogues—Theaetetōs (Theaetetus) and Sophistēs (Sophist)—the former being the major source of information about Theaetetus's life, including his death in a battle between Athens and Corinth in 369 BC.Theaetetus made important contributions to the mathematics that Euclid (fl. c. 300 BC) eventually collected and systematized in his Elements. A key area of Theaetetus's work was on (which correspond to irrational numbers in modern mathematics), in which he extended the work of Theodorus by devising the basic classification of incommensurable magnitudes into different types that is found in Book X of the Elements. He also discovered methods of inscribing in a sphere the five Platonic solids (Platonic solid) (tetrahedron, cube, octahedron, dodecahedron, and icosahedron), the subject of Book XII of the Elements. Finally, he may be the author of a general theory of proportion that was formulated after the numerically based theory of the Pythagoreans (Pythagoreanism) (fl. 5th century BC) yet before that of Eudoxus of Cnidus (c. 400–350 BC) as described in Book V of the 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 — Atheniensis ex iis, quorum alios pedibus, alios manibus, auribusque amputatis inustisque barbararum literarum notis, in longum sui ludibrium, reservaverant et in Perside locaverant. Curt. l. 5. c. 5. Item, Mathematicus, Olymp. 86. Scripsit… … Hofmann J. Lexicon universale
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
Theaetetus (mathematician) — Theaetetus (ca. 417 B.C. ndash; 369 B.C.) of Athens, son of Euphronius, of the Athenian deme Sunium, was a classical Greek mathematician. His principal contributions were on irrational lengths, which was included in Book X of Euclid s Elements ,… … Wikipedia
Theaetetus (dialogue) — The Theætetus (Greek: Θεαίτητος) is one of Plato s dialogues concerning the nature of knowledge. The framing of the dialogue begins when Euclides tells his friend Terpsion that he wrote a book many years ago based on what Socrates told him of a… … Wikipedia
Theaetetus (crater) — lunar crater data latitude=37.0 N or S=N longitude=6.0 E or W=E diameter=25 km depth=2.8 km colong=354 eponym=TheaetetusTheaetetus is a lunar impact crater that is located to the southeast of Cassini crater near the eastern edge of Mare Imbrium.… … Wikipedia
Theaetetus (cráter lunar) — Theaetetus Cráter lunar … Wikipedia Español
ТЕЭТЕТ — • Theaetētus, Θεαίτητος, 1. сын Евфория Сунийского, последователь Сократа, известный по названному его именем диалогу Платона и по «Софисту»; раньше он был учеником Феодора в Кирене. Он был очень щедр, хотя недобросовестные… … Реальный словарь классических древностей
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
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