Solve this:

$\left.\begin{array}{ccc}\mathrm{Q}\left(\mathrm{iii}\right). f\left(\theta \right)=\frac{1-\tan \mathrm{\theta }}{1-\sqrt{2 }\sin \mathrm{\theta }},& \mathrm{for}& \mathrm{\theta }\ne \frac{\mathrm{\pi }}{4}\\ =\frac{\mathrm{k}}{2},& \mathrm{for}& \mathrm{\theta }=\frac{\mathrm{\pi }}{4}\end{array}\right\} \mathrm{at} \theta =\frac{\mathrm{\pi }}{4}$