Write the principal value of `cos^(-1)(cos(2pi)/3)+sin^(-1)(s in(2pi)/3)`

Explanation

`cos^(-1)(cos(2pi)/3)=frac{2 pi}{3}` as `frac{2 pi}{3} in [0, pi]` but `frac{2 pi}{3} cancel(in)[frac{-pi}{2}, frac{pi}{2}]`

`:.cos^(-1)(cos(2pi)/3)+sin^(-1)(sin(2pi)/3)`

`=frac{2pi}{3}+sin^(-1)(sin(pi-(2pi)/3))`

`=frac{2 pi}{3}+sin^(-1)(sin(pi)/3)`

`frac{2 pi}{3}+frac{pi}{3}=pi`