please help me solve. I want to check if I missed a step in solving.

Determine the length of missing side by using pythagoras theorem.
[tex]\begin{gathered} x^2+(5)^2=(13)^2 \\ x^2=169-25 \\ x=\sqrt[]{144} \\ =12 \end{gathered}[/tex]Thus length of missing side is 12 cm. Option C is correct.