Q. The value of $\sin{\left( \sin^{- 1}{\frac{1}{3} + \sec^{- 1}3} \right) + \cos\left( \tan^{- 1}{\frac{1}{2} + \tan^{- 1}2} \right)}$ is

A) 1
B) 2
C) 3
D) 4
Explanation

(a)
$\sin{\left\lbrack \sin^{- 1}{\left( \frac{1}{3} \right) + \sec^{- 1}{(3)}} \right\rbrack + \cos\left\lbrack \tan^{- 1}\left( \frac{1}{2} \right) + \tan^{- 1}{(2)} \right\rbrack}$
$= \sin\left\lbrack \sin^{- 1}{\left( \frac{1}{3} \right) + \cos^{- 1}\left( \frac{1}{3} \right)} \right\rbrack\$
+$\cos\left\lbrack \tan^{- 1}{\left( \frac{1}{2} \right) + \cot^{- 1}\left( \frac{1}{2} \right)} \right\rbrack$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \sin{\frac{\pi}{2} + \cos\frac{\pi}{2}}$
$\left\lbrack \because\sin^{- 1}{x + \cos^{- 1}{x = \frac{\pi}{2}\ and\tan^{- 1}{x + \cot^{- 1}{x = \frac{\pi}{2}}}}} \right\rbrack$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 1$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

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