The hypotenuse of a right triangle is the longest side of the triangle, and it is always opposite to the right angle. It is the side that is directly opposite from the right angle and is located opposite from the triangle's adjacent and opposite sides. The hypotenuse is easy to identify as it is the side of the right triangle that is farthest from the vertex where the right angle is formed. In the Pythagorean Theorem, the hypotenuse is designated as the "c" side.
