$\arctan(\sqrt3/3)=\pi/6$: the special-angle identity $\tan(\pi/6)=1/\sqrt3$.Suggest a slogan
\(\arctan\qty{\frac{\sqrt3}{3}}=\frac{\pi}{6}\), because \(\tan\frac{\pi}{6}=\frac{1/2}{\sqrt3/2}=\frac{1}{\sqrt3}=\frac{\sqrt3}{3}\) and \(\frac{\pi}{6}\in\qty{-\frac{\pi}{2},\frac{\pi}{2}}\).
What is $\arctan\qty{\sqrt{3} \over 3}$?