Q. $\cos^{- 1}\left( \frac{- 1}{2} \right) - 2\sin^{- 1}{\left( \frac{1}{2} \right) + 3\cos^{- 1}\left( \frac{- 1}{\sqrt{2}} \right)}\ \ - 4\tan^{- 1}( - 1)$ equals

A) $\frac{19\pi}{12}$
B) $\frac{35\pi}{12}$
C) $\frac{47\pi}{12}$
D) $\frac{43\pi}{12}$
Explanation

(d)
$\cos^{- 1}{\left( - \frac{1}{2} \right) - 2\sin^{- 1}\left( \frac{1}{2} \right) + 3\cos^{- 1}{\left( - \frac{1}{\sqrt{2}} \right) + 4\tan^{- 1}{( - 1)}}}$
$\ = \pi - \cos^{- 1}{\left( \frac{1}{2} \right) - 2\left( \frac{\pi}{6} \right) + 3\left( \pi - \cos^{- 1}\left( \frac{1}{\sqrt{2}} \right) \right)}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ + 4\tan^{- 1}{(1)}$
$= \pi - \frac{\pi}{3} - \frac{\pi}{3} + 3\left( \pi - \frac{\pi}{4} \right) + 4.\frac{\pi}{4}$
$\ \ = \frac{\pi}{3} + 3.\frac{3\pi}{4} + \pi = \frac{43\pi}{12}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

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