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Born 1595 in Saint-Mihiel; died 1632 in The Hague. Dutch mathematician. Student of S. Stevin.
Girard was the first to state the fundamental theorem of algebra; he also examined negative and imaginary roots of equations on a par with positive roots. In his Treatise on Trigonometry (1626) he systematized all the theorems of plane and spherical trigonometry known up to that time.