Practicing Success
The value of $\tan ^{-1}\left[2 \cos \left(2 \sin ^{-1} \frac{1}{2}\right)\right]$ is : |
$\frac{\pi}{3}$ $\frac{\pi}{2}$ $\frac{\pi}{4}$ $\frac{\pi}{6}$ |
$\frac{\pi}{4}$ |
$\tan ^{-1}\left[2 \cos \left(2 \sin ^{-1} \frac{1}{2}\right)\right]$ $=\tan ^{-1}\left[2 \cos \left(2 \times \frac{\pi}{6}\right)\right]$ [Since $\sin^{-1}\frac{1}{2} = \frac{\pi}{6}$] $=\tan ^{-1}\left(2 \cos \left(\frac{\pi}{3}\right)\right)$ [Since $\cos\frac{\pi}{3} = \frac{1}{2}$] $=\tan ^{-1}\left(2 \times \frac{1}{2}\right)$ $=\tan ^{-1}(1)=\pi / 4$ $=\frac{\pi}{4}$ |