# Albert Girard

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**Albert Girard**was a French-born*mathematician*. He studied at the University of Leiden. He "had early thoughts on the fundamental theorem of algebra" and gave the inductive definition for the Fibonacci numbers. He was the first to use the abbreviations 'sin', 'cos' and 'tan' for the trigonometric functions in a treatise. Girard was the first to state, in 1632, that each prime of the form 1 mod 4 was the sum of two squares. It was said that he was quiet-natured and, unlike most mathematicians, did not keep a journal for his personal life.- also known as Жирар, Альбер
- born in (420 years ago) in Saint-Mihiel
- nationality: France
- education: Leiden University
- profession: Mathematician
- died on (383 years ago) in Leiden

**Albert Girard**was a Progressive Conservative party member of the Canadian House of Commons. His background was in business.- born on (66 years ago)
- nationality: Canada

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### Companion Encyclopedia of the History and Philosophy of the Mathematical Sciences (2002)

by Ivor Grattan-Guinness

**Albert Girard** called complex roots
solutions impossibles, but nevertheless formulated the fundamental theorem of
algebra, which states roughly that a polynomial of degree n has n roots. Although
given without proof, the theorem quickly became a mainstay of equation theory,
and thus helped ensure the complex and negative numbers permanent places in
the algebraic universe. Mathematicians, however, recognized that the usefulness
of ...

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