# If $0 < x< \large\frac{\pi}{2}$ and $\large\frac{\cos x}{1-\sin^2x} = \frac{5}{2}$, what is the value of $\cos x$?
$\begin{array}{1 1} (a)\;\frac{2}{5} \\ (b)\;\frac{3}{5} \\ (c)\;\frac{4}{5} \\ (d)\;\frac{6}{5}\end{array}$