(d) $\sin 2\theta = \cos \theta $

$\Rightarrow \cos \theta = \cos \left( {\frac{\pi }{2} – 2\theta } \right)$

$ \Rightarrow $ $\theta = 2n\pi \pm \left( {\frac{\pi }{2} – 2\theta } \right) $

$\Rightarrow \theta \pm 2\theta = 2n\pi \pm \frac{\pi }{2}$

$i.e.$, $3\theta = 2n\pi + \frac{\pi }{2} $

$\Rightarrow \theta = \frac{1}{3}\left( {2n\pi + \frac{\pi }{2}} \right)$

and $ – \theta = 2n\pi – \frac{\pi }{2}$

$\Rightarrow \theta = – \left( {2n\pi – \frac{\pi }{2}} \right)$

Hence value of $\theta $ between $0$ and $\pi $ are $\frac{\pi }{6},\,\frac{\pi }{2},\,\frac{{5\pi }}{6}$

$i.e.$, ${30^o},\,{90^o},\,{150^o}$.