Mathematics - Inverse Trigonometric Function Question with Solution | TestHub

Since maximum value of ${\cos }^{-1}x$ is $\pi$ Therefore, ${\cos }^{-1}x+{\cos }^{-1}y+{\cos }^{-1}z=3\pi \Rightarrow {\cos }^{-1}x={\cos }^{-1}y={\cos }^{-1}z=\pi$ $\Rightarrow x=y=z=-1\Rightarrow x^2+y^2+z^2-xy-yz-zx=0$