If $\alpha+\beta=\frac{\pi}{2}$ and $\beta+\gamma=\alpha$, then $\tan \alpha$ equals
If $\alpha+\beta=\frac{\pi}{2}$ and $\beta+\gamma=\alpha$, then $\tan \alpha$ equals
- $2(\tan \beta+\tan \gamma)$
- $\tan \beta+\tan \gamma$
- $\tan \beta+2 \tan \gamma$
- $2 \tan \beta+\tan \gamma$
Solution
Given, $\alpha=\beta+\gamma$
$\begin{aligned}
& \therefore \quad \gamma=\alpha-\beta \\
& \quad \begin{aligned}
\tan \gamma & =\tan (\alpha-\beta) \\
& =\frac{\tan \alpha-\tan \beta}{1+\tan \alpha \cdot \tan \beta}
\end{aligned}
\end{aligned}$
$\begin{aligned}
& =\frac{\tan \alpha-\tan \beta}{1+\tan \alpha \cdot \tan \left(\frac{\pi}{2}-\alpha\right)} \quad \cdots\left[\begin{array}{l}
\alpha+\beta=\frac{\pi}{2} \\
\therefore \beta=\frac{\pi}{2}-\alpha
\end{array}\right] \\
& =\frac{\tan \alpha-\tan \beta}{1+\tan \alpha \cot \alpha} \\
& =\frac{\tan \alpha-\tan \beta}{2}
\end{aligned}$
$\begin{aligned}
& \Rightarrow 2 \tan \gamma=\tan \alpha-\tan \beta \\
& \Rightarrow \tan \alpha=2 \tan \gamma+\tan \beta
\end{aligned}$
Asked in: MHT CET 2024 (09 May Shift 1)
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