**Bartholomeo Pitiscus** was a Polish theologian who first coined the word *Trigonometry*.

- Pitiscus's future was much tied to Friedrich der Aufrichtige, known as Frederick IV, elector of the Palatine of the Rhine.
- John Casimir was an ardent Calvinist and appointed Pitiscus to teach Frederick in 1584.
- Later Pitiscus was appointed court chaplain at Breslau and court preacher to Frederick IV.
- Pitiscus strongly supported the Calvinist policies from a major position of influence.
- The word 'trigonometry' is due to Pitiscus and first occurs in the title of his work Trigonometria: sive de solutione triangulorum tractatus brevis et perspicuus first published in Heidelberg in 1595 as the final section of A Scultetus's Sphaericorum libri tres methodicé conscripti et utilibus scholiis expositi.
- In 1600 a revised version of Pitiscus's work was published in Augsburg as Trigonometriae sive de dimensione triangulorum libri quinque.
- Perhaps we should note that Pitiscus actually calls these 'axioms' rather than 'theorems' but they are theorems in the usual sense given with proofs.
- First written in Latin, by Bartholomew Pitiscus of Grunberg in Silesia, and now translated into English by Ralph Handson.
- Pitiscus was not the first to publish tables of all six trigonometric functions.
- Pitiscus was engaged to correct the tables.
- First Pitiscus had to find a manuscript copy of Rheticus's tables which he did after the death of Valentinus Otho (in 1603).
- He recomputed all the tangents and secants between 83° and 90° to eleven decimal places and 86 pages of Opus Palatinum de triangulis was reprinted incorporating Pitiscus's corrections.
- Pitiscus then began to work on a new project incorporating his own work with that of Rheticus.
- The Thesaurus mathematicus was eventually published in 1613 and contained a table of sines by Rheticus calculated for every 10'' to fifteen decimal places; a calculation of the sine at 1'' intervals for the first and last degree of the quadrant, again by Rheticus to fifteen decimal places; values for the basic sines from which the others were calculated to 22 decimal places by Pitiscus; and sines to 22 decimal places by Pitiscus for each tenth, thirtieth, and fiftieth second in the first 35 minutes.

Born 24 August 1561, Grünberg, Bohemia (now Zielona Góra, Poland). Died 2 July 1613, Heidelberg, Electoral Palatinate (now Germany).

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Analysis, Astronomy, Geometry, Origin Poland

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive