- $f\left( {\frac{\pi }{3}} \right) \in \left( {2;3} \right)$.
- $f\left( {\frac{\pi }{3}} \right) \in \left( {3;4} \right)$.
- $f\left( {\frac{\pi }{3}} \right) \in \left( {4;6} \right)$.
- $f\left( {\frac{\pi }{3}} \right) \in \left( {1;2} \right)$.