Question

The value of $\cos^{-1}(\frac{1}{2}) + \cos^{-1}(\frac{1}{2})$ is

• A. 0
• B. $\frac{\pi}{3}$
• C. $\frac{\pi}{6}$
• D. $\pi$

Answer 1

None of the given options (the correct value is $\frac{2\pi}{3}$)

Answer 2

We know that

$\cos^{-1}\left(\frac{1}{2}\right)=\frac{\pi}{3}$.

Thus,

$\cos^{-1}\left(\frac{1}{2}\right)+\cos^{-1}\left(\frac{1}{2}\right)=\frac{\pi}{3}+\frac{\pi}{3}=\frac{2\pi}{3}$.

None of the given options (0, $\frac{\pi}{3}$, $\frac{\pi}{6}$, $\pi$) equals $\frac{2\pi}{3}$.