# In a right triangle, one angle measures $x^{\circ}$ where $\sin x = \large\frac{4}{5},$ what is the $\cos (90^{\circ}-x).$ ?
$\begin{array}{1 1} (a)\;\frac{4}{5}\\ (b)\; \frac{-4}{5}\\ (c)\;\frac{5}{4}\\ (d)\; \frac{3}{5} \end{array}$