Mathematician:Albert Girard

Mathematician
Professional French lutenist who also studied mathematics, working in the fields of algebra, trigonometry and arithmetic.

Gave an inductive formula for the Fibonacci numbers.

First stated in $1632$ that every prime of the form $4 k + 1$ is the sum of two squares in only one way. Invented the symbol $\sqrt[n]x$ for the $n$th root of $x$.

Also introduced the symbols $\sin$, $\cos$ and $\tan$.

His work led eventually to the creation of group theory.

Nationality
French

History

 * Born: 1595 in St Mihiel, France.
 * Died: 8 Dec 1632 in Leiden, Netherlands.

Theorems

 * Girard's Theorem
 * Newton-Girard Formulas (with )

Publications

 * 1625: A French translation of the works of


 * 1625: A French translation of Books $\text V$ and $\text {VI}$ of 's (the  edition)

(titles unknown)
 * 1626: A treatise on trigonometry


 * 1629: