Mathematics

Problem

\sin^{-1}x + \cot^{-1}\left(\frac{1}{2}\right) = \frac{\pi}{2}

, then

x

is equal to (a) 0 (b)

\frac{1}{\sqrt{5}}

(c)

\frac{2}{\sqrt{5}}

(d)

\frac{\sqrt{3}}{2}