In the previous post we talked about initial concepts about triangles. Now, let’s talk about properties, specifically about the congruence of triangles. History The congruence of triangles is a fundamental concept in geometry, and its discovery dates back many centuries ago. Let’s explore a little of this story: Euclid and the Elements: The Greek mathematician Euclid, around 300 BC, formalized the principles of geometry in his famous book “The Elements”. In this work, he established the criteria for the congruence of triangles, as LLL - Side Side Side, LAL - Side Angle Side, ALA - Angle Side Angle and LAAo - Side Angle Opposite angle. These criteria are known as “congruence postulates”.