What area of math did Leonardo da Vinci study?

He was one of the developers of the golden ratio. He showed this in his painting The Vitruvian Man. (the golden ratio is kind of like pi 3.14... and I think the g. ratio is 1.168...) The golden ratio is a mathematical number that is suppose to describe the ratio between everything males to females or arm length to elbow to shoulder length (something like that)