Viète, François

(1540-1603)

   French mathematician, important for the development of trigonometric tables and algebraic notation. The son of a lawyer and notary at Fontenay-le-Comte in Poitou, he was educated in law at Poitiers, receiving a baccalaureate in 1560 but abandoning that profession in 1564 to become tutor to the daughter of an important noble family. He moved to Paris in 1570, and in 1573 King Charles IX appointed him counsellor in the Parlement of Rennes, where he remained for six years. In 1580 Viète became a privy councillor and maître des requêtes in the Parlement of Paris. Having been banished from court through the influence of political enemies, he spent the years 1584-1585 in the provinces. After the ac-cession of King Henry IV in 1589, he returned to court, deciphering coded messages captured during the war with Spain. In 1602, how-ever, he was dismissed from royal service.

   Viète's first mathematical tract, Principes de cosmographie, began as one of his lectures as a tutor. Other works include Canon mathe-maticus seu Ad triangula (1579), In artem analyticam isagoge (1591), and De aequationum recognitione et emendatione (1615), ed-ited and posthumously published by a Scottish friend. Viète's mathe-matical innovations include being the first mathematician to use let-ters of the alphabet to represent known and unknown quantities, invention of the term "coefficient," and use of the cosine law for plane triangles. He also published the law of tangents. In 1592-1595 he engaged in a public dispute with the noted scholar Josephus Jus-tus Scaliger, who erroneously claimed to have solved the problem of squaring the circle.