Respuesta :
[tex]\bf \textit{pythagorean theorem}\\\\\\
c^2=a^2+b^2\implies c=\sqrt{a^2+b^2}\qquad
\begin{cases}
c=hypotenuse\\
a=\textit{one side}\\
b=\textit{the other side}
\end{cases}[/tex]
The answer is 13. This is a common set of right triangle combinations as a 5-12-13. Another is 3-4-5, but I'll show how to get 13 using Pythagoras.
a^2 + b^2 = c^2
5^2 + 12^2 = c^2
25 + 144 = c^2
169 = c^2
c = 13
a^2 + b^2 = c^2
5^2 + 12^2 = c^2
25 + 144 = c^2
169 = c^2
c = 13