The value of $\tan \left(\frac{\pi}{8}\right)$ is

The value of $\tan \left(\frac{\pi}{8}\right)$ is
  1. $\sqrt{2}-1$
  2. $1-\sqrt{2}$
  3. $\sqrt{2}$
  4. $\sqrt{2}+1$

Solution

Since, $\tan \frac{A}{2}=\frac{1-\cos A}{\sin A}$ Putting $\frac{\mathrm{A}}{2}=\frac{\pi}{8}$, we get $\begin{aligned} \tan \left(\frac{\pi}{8}\right) & =\frac{1-\cos \frac{\pi}{4}}{\sin \frac{\pi}{4}} \\ & =\frac{1-\frac{1}{\sqrt{2}}}{\left(\frac{1}{\sqrt{2}}\right)} \\ \therefore \quad \tan \left(\frac{\pi}{8}\right) & =\sqrt{2}-1\end{aligned}$

Asked in: MHT CET 2023 (11 May Shift 1)

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