Question: If
$y(\alpha)=\sqrt{2\left(\frac{\tan \alpha+\cot \alpha}{1+\tan ^{2} \alpha}\right)+\frac{1}{\sin ^{2} \alpha}}, \alpha \in\left(\frac{3 \pi}{4}, \pi\right)$
then $\frac{d y}{d \alpha}$ at $\alpha=\frac{5 \pi}{6}$ is :
4
$-\frac{1}{4}$
$\frac{4}{3}$
$-4$
Correct Option: 1
Solution:
