3.Trigonometrical Ratios, Functions and Identities
hard

If $\frac{\sqrt{2} \sin \alpha}{\sqrt{1+\cos 2 \alpha}}=\frac{1}{7}$ and $\sqrt{\frac{1-\cos 2 \beta}{2}}=\frac{1}{\sqrt{10}}$ $\alpha, \beta \in\left(0, \frac{\pi}{2}\right),$ then $\tan (\alpha+2 \beta)$ is equal to

A

$1$

B

$2$

C

$2.5$

D

$3.5$

(JEE MAIN-2020)

Solution

$\frac{\sqrt{2} \sin \alpha}{\sqrt{2} \cos \alpha}=\frac{1}{7} \Rightarrow \tan \alpha=\frac{1}{7}$

$\sin \beta=\frac{1}{\sqrt{10}} \Rightarrow \tan \beta=\frac{1}{3} \Rightarrow \tan 2 \beta=\frac{3}{4}$

$\tan (\alpha+2 \beta)=\frac{\tan \alpha+\tan 2 \beta}{1-\tan \alpha \tan 2 \beta}=1$

Standard 11
Mathematics

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