what is cot(A) if cos(A)=2/radical(13)

what is cot(A) if cos(A)=2/radical(13)

$\begin{array}{|rcll|} \hline \cos(A)&=& \frac{2} { \sqrt{13} } \\\\ 2^2+x^2 &=& ( \sqrt{13} ) ^2 \\ 4 + x^2 &=& 13 \\ x^2 &=& 13 -4 \\ x^2 &=& 9 \\ x &=& 3 \\\\ \cot(A) &=& \frac{2}{3} \\ \hline \end{array}$