The longest side of a right triangle is called the hypotenuse.
The hypotenuse is the side opposite the right angle, which is always the largest side in a right triangle. According to the Pythagorean theorem, the relationship between the lengths of the sides of a right triangle can be expressed as a² + b² = c², where c represents the length of the hypotenuse, and a and b represent the lengths of the other two sides. This fundamental property is essential in various applications of geometry and trigonometry.