Greek mathematician, born around 325 BC and died about 265 BC in Alexandria, author of elements of geometry, one of the most important and influential in the history of mathematics.

Despite being one of the most important mathematicians of antiquity, his life is virtually unknown, even has come to speculate about the existence of their historical figure. Lived in Alexandria (Egypt) during the reign of the Pharaoh Ptolemy I Soter (367-282 BC) Hellenistic and founded the school of mathematics of this city. Given the knowledge that shows in his works, thought that he/she studied physics, astronomy and mathematics in the Platonic School of Athens.

One of the few stories that are known of his life is the answer that gave the Pharaoh Ptolemy I when it asked if there was a simple way to learn geometry that were not studying the elements, to which, according to legend, Euclid replied: "in geometry there are no straight roads reserved for Kings".

Euclid, author of elements of geometry

While working in Alexandria, Euclid wrote elements of geometry, as a result of the gathering, confrontation and enlargement of the mathematical concepts known in his time. But in addition to systematize knowledge of times, Euclid created a new logical management based on the axiomatic method, according to which everything follows from a set of axioms and five postulates whose truth is considered self-evident. The five principles are as follows:

1. it is possible to draw a straight line between two points cualesquiera.2. All segment can be extended indefinitely in line recta.3. A circle can have any Center and any radio.4. All right angles are iguales.5. A parallel line only passes through a point outside a straight.

Elements of geometry consists of thirteen books: the first six are about geometry flat, most important part of this work; are covered in the following four subjects of arithmetic, they explained, for example, the famous method of calculating the greatest common divisor of two numbers known as the Euclid's algorithm; the last three books contain results on geometry in three dimensions.

This way of organizing the mathematical knowledge is still a very important pillar in the structure of current mathematics. In fact, the postulates that splits the elements have been considered for over two thousand years the basis of geometry.For more information see the **Euclidean geometry** geometry voice.

In the 19th century, as a result of work on Riemanniangeometry, was questioned the need for the fifth in the postulates of Euclid, which resulted in what is known as geometry not Euclidean.

Other works attributed to Euclid are data, optics, divisions of surfaces, music elements and phenomena.