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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