# How do you solve arccos(cos 2pi)?

$2 \pi$
arccos or ${\cos}^{-} 1 x$ and cosx are $\textcolor{b l u e}{\text{inverse functions}}$
and $\textcolor{red}{| \overline{\underline{\textcolor{w h i t e}{\frac{a}{a}} \textcolor{b l a c k}{{f}^{-} 1 \left(f \left(x\right)\right) = x} \textcolor{w h i t e}{\frac{a}{a}} |}}}$
$\Rightarrow \arccos \left(\cos \left(2 \pi\right)\right) = 2 \pi$