One of the most famous discoveries in ancient Greece is the Pythagorean theorem, which states that in a right-angled triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides. This theorem, which can be expressed as a²+b² = c², remains a fundamental concept in mathematics today and has had a lasting impact on geometry and our understanding of spatial relationships.