!$ \left [ \dfrac{ \pi}{6}, \dfrac{ 5 \pi}{6} \right ] \quad !$

!$ \left [ \dfrac{ \pi}{6}, \dfrac{ 7 \pi}{6} \right ] \quad !$

!$ \left [ \dfrac{ 5 \pi}{6}, \dfrac{ 11 \pi}{6} \right ] \quad !$

!$ \left [ \dfrac{ 7 \pi}{6}, \dfrac{ 11 \pi}{6} \right ] \quad !$