To determine the length of the unknown side of the right triangle, we need more information about the triangle, such as the lengths of the known sides or whether it's asking for the length of the hypotenuse or one of the legs.
Commonly, the Pythagorean theorem is used for right triangles, which states:
\[ a^2 + b^2 = c^2 \]
where \(c\) is the length of the hypotenuse and \(a\) and \(b\) are the lengths of the other two sides.
If you provide the lengths of the other sides or indicate which side is unknown, I can help calculate it for you.