To determine the hypotenuse of the triangle.
The hypotenuse is the opposite side of the right angle in the triangle. It’s also the longest side of the triangle.
If a problem says that to calculate the length of hypotenuse c in a triangle with side a, side b, and hypotenuse c.
Then you are working with a right-angled triangle.
Then by Pythagoras theorem, determine the hypotenuse.

![c=\sqrt[]{a^2+b^2}](https://img.qammunity.org/2023/formulas/mathematics/college/6uwqakmkjq6nua21bpopztkrf20jt2flji.png)
Then the hypotenuse side is calculated.