Accredited for the proof of corresponding sides of similar triangles and that they are proportional. Introduced abstract Geometry.

Accredited for the Pythagorean Theorem. He discovered that the sum of all the angles in a triangle equal 180 degrees.

Created the first organized textbook on geometry.

Zeno wrote out his paradoxes. There were four paradoxes; The Dichotomy, The Achilles, The Arrow, and The Stade (Stadium).

The beginning of the use of numerals.

Comparing Irrational and Rational lengths by cross multiplication.

"Father of Geometry"! He was the creator of Euclidean Geometry. He also wrote the famous book, The Elements. It is a collection of 13 books.

He analyzed the area of a circle. He also found how to calculate SA and the Volume of spheres and cylinders.

The estimation of the circumference of the Earth. They were only off by 15% to what the circumference is known today.

Found the formula for the area of a quadrilateral.

Synthesized geometry by placing points on a coordinate plane.

Creator of Non-Euclidean geometry.

Made significant contributions to differential geometry.