Question
If $\tan 15^\circ + {1 \over {\tan 75^\circ }} + {1 \over {\tan 105^\circ }} + \tan 195^\circ = 2a$, then the value of $\left( {a + {1 \over a}} \right)$ is :
If $\tan 15^\circ + {1 \over {\tan 75^\circ }} + {1 \over {\tan 105^\circ }} + \tan 195^\circ = 2a$, then the value of $\left( {a + {1 \over a}} \right)$ is :