Dec 2

Duke Johann Wilhelm of SaxeAltenburg
a member of the Ernestine branch of the House of Wettin and a titular Duke of SaxeAltenburg and of JülichClevesBerg.

Dec 8

Albert Girard
a Frenchborn 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 quietnatured and, unlike most mathematicians, did not keep a journal for his personal life

Dec 8

Philippe van Lansberge
a Dutch Calvinist Minister, astronomer and Mathematician.
His name is sometimes written Lansberg, and his first name is sometimes given as Philip or Johannes Philippus. He published under the Latin name Philippus Lansbergius
