Euclid (Greek: ε υ κ λ ε ι δ η, 330 BC-275 BC) was an ancient Greek mathematician. He was active in Alexandria during the period of Ptolemy I Soter (364 BC-283 BC) and was called "the father of geometry". His most famous book, The Elements of Geometry, is the foundation of European mathematics, and puts forward five formulas, Euclid Geometry, which is widely regarded as the most successful textbook in history. Euclid also wrote some works on conic curves, spherical geometry and number theory.

Anecdotal allusions

At that time, people built tall pyramids, but no one knew how high they were. Someone said, "It is more difficult to measure the height of the pyramid than to climb to the sky!" " "This word reached the ears of Euclid. He smiled and told others, "What's so hard about this? When your shadow is as long as your body, measure how long the shadow of the pyramid is, and the length is equal to the height of the pyramid! "