If $\tan \theta+\tan 2 \theta+\sqrt{3} \tan \theta \tan 2 \theta=\sqrt{3}$, then the general values of…

If $\tan \theta+\tan 2 \theta+\sqrt{3} \tan \theta \tan 2 \theta=\sqrt{3}$, then the general values of $\theta$ are
  1. $(3 n+1) \frac{\pi}{3}, n \in Z$
  2. $(3 n+1) \frac{\pi}{9}, n \in Z$
  3. $(3 n+1) \frac{\pi}{6}, n \in Z$
  4. $(2 n+1) \frac{\pi}{9}, n \in Z$

Solution

It is given that $ \begin{aligned} & \tan \theta+\tan 2 \theta+\sqrt{3} \tan \theta \tan 2 \theta=\sqrt{3} \\ & \Rightarrow \frac{\tan \theta+\tan 2 \theta}{1-\tan \theta \tan 2 \theta}=\sqrt{3}=\tan \frac{\pi}{3} \\ & \Rightarrow \tan (3 \theta)=\tan \frac{\pi}{3} \Rightarrow 3 \theta=n \pi+\frac{\pi}{3}, n \in Z \\ & \Rightarrow \theta=(3 n+1) \frac{\pi}{9}, n \in Z \end{aligned} $ Hence, option (b) is correct

Asked in: AP EAMCET 2019 (20 Apr Shift 2)

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