# Euclid

## Who was he?

Almost nothing is known about him other than that he wrote the Elements, a series of books defining our common geometry axioms, or theories. Aside from this we we know that he was a student at the School of Athens between the Plato and Archimedes. He was taught there sometime between 347 B.C. and 287 B.C.

We know that he taught at Alexandria, the capital city of ancient Egypt and home to a legendary library. It is believed that he taught there sometime between 320 B.C. and 260 B.C.

The rest of his life must be left up to guesswork. Most people believe he was born around 300 B.C which would make him older than Archimedes, another Greek Mathematician, who was born in 290 B.C. Some historians don't support this belief, though. So no one is even sure of that.

Euclid's Windmill Proof

This is the proof Euclid included in the Elements for the Pythagorean Theorem.

Book II, Proposition 5

This is one of the oldest pieces of the the Elements. a scrap of papyrus from around A. D. 100. The diagram in the lower corner is from Book II, Proposition 5.

## What did he do?

Euclid is most famous for his treatise on geometry, the Elements. It was a series of 13 books that contained the basis of plane geometry. In it he defined basic aspects of geometry such as what a line is or what a point is. It also provided proofs for things like the pythagorean theorem.

## Why do I have to know about him?

Euclid basically invented normal geometry. Anytime you plot a point or draw a line, you are practicing euclidian Geometry. Euclidian Geometry is the kind you were taught in 8th grade Geometry class. In it everything is based on a flat plane.

Non-Euclidian geometry is based on a sphere and is much more complex but much less practical.