If $y=\sin \left(x^{x}\right)$, prove that $\frac{d y}{d x}=\cos \left(x^{x}\right) \cdot x^{x}(1+\log x)$
Here,
$y=\sin \left(x^{x}\right) \ldots \ldots$ (i)
Let $u=x^{x} \ldots \ldots$ (ii)
Taking log on both sides,
$\log u=\log x^{x}$
$\log u=x \log x$
Differentiating both sides with respect to $x$,
$\frac{1}{\mathrm{u}} \frac{\mathrm{du}}{\mathrm{dx}}=\frac{\mathrm{d}}{\mathrm{dx}}(\mathrm{x} \log \mathrm{x})$
$=x \frac{d}{d x}(\log x)+\log x \frac{d}{d x}(x)$
$=x\left(\frac{1}{x}\right)+\log x(1)$
$\frac{1}{u} \frac{d u}{d x}=1+\log x$
$\frac{d u}{d x}=u(1+\log x)$
$\frac{d u}{d x}=x^{x}(1+\log x) \ldots \ldots$ (iii) [from (ii)]
Now, using equation (ii) in (i)
$y=\sin u$
Differentiating both sides with respect to $\mathrm{x}$,
$\frac{d y}{d x}=\frac{d}{d x}(\sin u)$
$=\cos u \frac{d u}{d x}$
Using equation (ii) and (iii),
$\frac{d y}{d x}=\cos x^{x} \cdot x^{x}(1+\log x)$
Hence Proved.