Hypotenuse

The hypotenuse of a right triangle is the longest side of the right triangle.

It is the side opposite the right angle.

A common problem you see is to find the hypotenuse of a right triangle given the lengths of its other 2 sides. For example, what is the hypotenuse (C) of a right triangle whose other 2 sides (A and B) are 3 inches and 4 inches?
The equation for that (the Pythagorean theorem) is
C² = A² + B². So,
C² = 3² + 4²
C² = 25, so C = √25 = 5

Now, here's a problem for you:
Find the length of the hypotenuse in this right triangle:
a = 5, b = 12
c² = 5² + 12² = _______
c = ________________

To learn more about types of triangles see the triangle notes.