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Euclid , another name Euclid of Alexandria and also known as Father of Geometry. A Greek mathematician known for the major contribution on geometry. The whole new stream of geometry established by him known as Euclidean Geometry. Basically the modern 2 dimension geometry (mean what u can draw on a paper) is actually adopted from the Euclidean Geometry. and also it is the basic building block of the modern geometry.
All of his invents and developments , axioms etc. are written on his book "Euclid's Elements" that consisting 13 book. This is one of the most influential and successful textbook ever written.
He also works of Number Theory, Spherical Geometry, Conic Section etc.