Answer
$\frac{dy}{dx} =\frac{cos x}{2 \sqrt {sinx}}$
Work Step by Step
$\frac{dy}{du} = \frac{d(\sqrt u)}{du} = \frac{1}{2\sqrt u}$
and,
$\frac{du}{dx} = \frac{d(sin x)}{dx} = cos x$
So,
$\frac{dy}{dx} = \frac{dy}{du}*\frac{du}{dx}$
$\frac{dy}{dx} =\frac{cos x}{2 \sqrt {u}}$
$\frac{dy}{dx} =\frac{cos x}{2 \sqrt {sinx}}$