Q. If $\cos{\theta = - \frac{\sqrt{3}}{2}}$ and $\sin{\alpha = - \frac{3}{5}}$, where $\theta$ does not lie in the third quadrant, then $\frac{2\tan{\alpha + \sqrt{3}\tan\theta}}{\cot^{2}{\theta + \cos\alpha}}$ is equal to

A) $\frac{7}{22}$
B) $\frac{5}{22}$
C) $\frac{9}{22}$
D) $\frac{22}{5}$
Explanation

(b)
Given, $\cos{\theta = - \frac{\sqrt{3}}{2} < 0}$ and $\theta$ does not lie in third quadrant.
$\therefore\ \ \theta$ must be lying in 2nd quadrant
$\Rightarrow \ \tan{\theta = - \frac{1}{\sqrt{3}}}$ and $\cot{\theta = - \sqrt{3}}$ …(i)
Also, $\alpha$ lies in 3rd quadrant and $\sin{\alpha = - \frac{3}{5}}$
$\therefore\ \tan{\alpha = \frac{3}{4}}$ and $\cos{\alpha = - \frac{4}{5}}$ …(ii)
$\therefore\ \ \frac{2\tan{\alpha + \sqrt{3}\tan\theta}}{\cot^{2}{\theta + \cos\alpha}} = \frac{2.\frac{3}{4} - \sqrt{3} - \frac{1}{\sqrt{3}}\ }{3 - \frac{4}{5}} = \frac{5}{22}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.