# Which mathematician is known for having formulated the principle that the sum of the interior angles of a triangle is always equal to 180 degrees?

Euclid

This fundamental principle of geometry was systematized by Euclid in his "Elements," a set of thirteen books that constitute one of the most influential works in the history of mathematics. Euclid, often considered the "father of geometry," compiled and extended the geometric knowledge of his time, establishing the foundations of Euclidean geometry. His work not only served as a fundamental text for the teaching of mathematics for centuries but also raised essential questions about the nature and properties of space. Euclid's "Elements" remain a testament to human ingenuity in the quest for order and understanding of the natural world.