Question : If $\tan (\alpha+\beta)=a, \tan (\alpha-\beta)=b$, then the value of $\tan 2 \alpha$ is:
Option 1: $\frac{a+b}{1-a b}$
Option 2: $\frac{a+b}{1+a b}$
Option 3: $\frac{a-b}{1+a b}$
Option 4: $\frac{a-b}{1-a b}$
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Correct Answer: $\frac{a+b}{1-a b}$
Solution : Given, $\tan (\alpha+\beta)=a$ and $\tan (\alpha-\beta)=b$ $\tan{2\alpha}=\tan((\alpha + \beta)+(\alpha - \beta)) = \frac{\tan(\alpha+\beta) + \tan(\alpha - \beta)}{1-\tan(\alpha + \beta)\tan(\alpha - \beta)}= \frac{a+b}{1-ab}$ Hence, the correct answer is $\frac{a+b}{1-ab}$.
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Question : If $\tan(\alpha -\beta)=1,\sec(\alpha +\beta)=\frac{2}{\sqrt{3}}$ and $\alpha ,\beta$ are positive, then the smallest value of $\alpha$ is:
Option 1: $142\frac{1}{2}°$
Option 2: $187\frac{1}{2}°$
Option 3: $7\frac{1}{2}°$
Option 4: $37\frac{1}{2}°$
Question : If $\alpha+\beta=90^{\circ}$ and $\alpha=2 \beta$, then the value of $3 \cos ^2 \alpha-2 \sin ^2 \beta$ is equal to:
Option 1: $\frac{3}{4}$
Option 2: $\frac{3}{2}$
Option 3: $\frac{1}{4}$
Option 4: $\frac{4}{3}$
Question : If $\tan (\alpha+\beta)=\sqrt{3}, \tan (\alpha-\beta)=1$ where $(\alpha+\beta)$ and $(\alpha-\beta)$ are acute angles, then what is $\tan$ $(6 \alpha) ?$
Option 1: $-1$
Option 2: $0$
Option 3: $1$
Option 4: $\sqrt{2}-1$
Question : If $\tan 40^{\circ}=\alpha$, then find $\frac{\tan 320^{\circ}-\tan 310^{\circ}}{1+\tan 320^{\circ} \cdot \tan 310^{\circ}}$.
Option 1: $\frac{1-\alpha^2}{\alpha}$
Option 2: $\frac{1+\alpha^2}{2 \alpha}$
Option 3: $\frac{1-\alpha^2}{2 \alpha}$
Option 4: $\frac{1+\alpha^2}{a}$
Question : What is $\sin \alpha - \sin\beta$?
Option 1: $2 \cos \frac{\alpha+\beta}{2} \sin \frac{\alpha-\beta}{2}$
Option 2: $2 \sin \frac{\alpha+\beta}{2} \sin \frac{\alpha-\beta}{2}$
Option 3: $2 \cos \frac{\alpha-\beta}{2} \sin \frac{\alpha+\beta}{2}$
Option 4: $2 \cos \frac{\alpha+\beta}{2} \cos \frac{\alpha-\beta}{2}$
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