In a right traiangles, note that the longest side or the side facing the 90degrees is the hypotenuse.
Also, the side facing a given angle is the opposite
Then, the last side is adjacent.
Also, note the pythagorean theorem that;

Also note the concept below;

As explained y represents the hypotenuse because it is the longest side,
x represents the opposite side because it faces the given angle,
so 13 is the adjacent.
First, using TOA concept to get x;

On getting x=13, the pythagoream theorem can be used to get the third side called the hypotenuse.
![\begin{gathered} h^2=o^2+a^2 \\ y^2=13^2+13^2 \\ y^2=169+169 \\ y^2=338 \\ y=\sqrt[]{338} \\ y=18.4 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/rdg9b68a59yo6khp7y91yudhb7kzpna229.png)