Question

Solve : ${\cos }^{-1}(-\frac{1}{2})$

Answer 1

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