MCQ
Find the value of $\tan ^{-1}\left(2 \cos \left(2 \sin ^{-1} \frac{1}{2}\right)\right)$.
  • A
    $\frac{\pi}{3}$
  • $\frac{\pi}{4}$
  • C
    $\frac{\pi}{2}$
  • D
    $\frac{\pi}{6}$

Answer

Correct option: B.
$\frac{\pi}{4}$
(b) : We have,
$
\begin{array}{l}
\tan ^{-1}\left\{2 \cos \left(2 \sin ^{-1}\left(\frac{1}{2}\right)\right)\right\}=\tan ^{-1}\left\{2 \cos \left(2 \times \frac{\pi}{6}\right)\right\} \\
=\tan ^{-1}\left\{2 \cos \frac{\pi}{3}\right\}=\tan ^{-1}\left[2 \times \frac{1}{2}\right]=\tan ^{-1} 1=\frac{\pi}{4} \\
\end{array}
$

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