Q. $\cos\left\lbrack \cos^{- 1}{\left( - \frac{1}{7} \right) + \sin^{- 1}\left( - \frac{1}{7} \right)} \right\rbrack$ is equal to
A) $- \frac{1}{3}$
B) 0
C) $\frac{1}{3}$
D) $\frac{4}{9}$
Explanation
(b)
$\cos{\left\lbrack \cos^{- 1}{\left( - \frac{1}{7} \right) + \sin^{- 1}\left( - \frac{1}{7} \right)} \right\rbrack = \cos\frac{\pi}{2}}$
$\left\lbrack \because\cos^{- 1}{x = + \sin^{- 1}{x = \frac{\pi}{2}}} \right\rbrack$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 0$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.