If y=\sin (\sqrt{\sin x+\cos x}) , find \frac{d y}{d x} .
Putting (\sin x+\cos x)=t and \sqrt{(\sin x+\cos x)}=\sqrt{t}=u , we get
y=\sin u, u=\sqrt{t} \text { and } t=(\sin x+\cos x) .\\ \\ \therefore \quad \frac{d y}{d u}=\cos u, \frac{d u}{d t}=\frac{1}{2} t^{-1 / 2}=\frac{1}{2 \sqrt{t}}
and \frac{d t}{d x}=(\cos x-\sin x) .