François Viete, born in Fontenay-le-compte in 1540 firstly achieved his law diploma in 1960. But concurrently of his juridical career, he is interested in sciences. In that way he wrote an astonomy treatise ("Principes de cosmographie"). But as he was banished in 1584 for 5 years, having some "free time" he starts to take interest in mathematics !
It was his most productive period. Working on algebra and mainly on polynomials, he rather simplifies notations and discovers a third-degree-equation solving method. He is also interested in the expression of cos(nx) and sin(nx) in terms of cos(x) and sin(x), he obtained what we call today Tchebychev's polynomials.