If $\frac{1-\tan \theta}{1+\tan \theta}=\frac{1}{\sqrt{3}}$, where $\theta \in\left(0, \frac{\pi}{2}\right)$…

If $\frac{1-\tan \theta}{1+\tan \theta}=\frac{1}{\sqrt{3}}$, where $\theta \in\left(0, \frac{\pi}{2}\right)$, then $\theta=$
  1. $\frac{\pi}{12}$
  2. $\frac{\pi}{4}$
  3. $\frac{\pi}{6}$
  4. $\frac{\pi}{3}$

Solution

Given $\frac{1-\tan \theta}{1+\tan \theta}=\frac{1}{\sqrt{3}}$ $\therefore \tan \left(\frac{\pi}{4}-\theta\right)=\frac{1}{\sqrt{3}}$ Comparing with $\tan \frac{\pi}{6}=\frac{1}{\sqrt{3}}$, we write $\begin{aligned} & \frac{\pi}{4}-\theta=\frac{\pi}{6} \\ \therefore & \theta=\frac{\pi}{4}-\frac{\pi}{6}=\frac{\pi}{12} \end{aligned}$

Asked in: MHT CET 2020 (14 Oct Shift 1)

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