Evaluate:
\({\cos ^{ - 1}}\left( {\cos \left( {\frac{{7\pi }}{6}} \right)} \right) = \;?\)
1
\(\frac{{7\pi }}{6}\)
2
\(\frac{{\pi }}{6}\)
3
\(\frac{{5\pi }}{6}\)
4
\(\frac{{\pi }}{3}\)
Evaluate:
\({\cos ^{ - 1}}\left( {\cos \left( {\frac{{7\pi }}{6}} \right)} \right) = \;?\)