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MHT CET · Maths · Trigonometric Equations

If \(\alpha+\beta=\frac{\pi}{2}\) and \(\beta+\gamma=\alpha\), then \(\tan \alpha\) equals

  1. A \(2(\tan \beta+\tan \gamma)\)
  2. B \(\tan \beta+\tan \gamma\)
  3. C \(\tan \beta+2 \tan \gamma\)
  4. D \(2 \tan \beta+\tan \gamma\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\tan \beta+2 \tan \gamma\)

Step-by-step Solution

Detailed explanation

Given, \(\alpha=\beta+\gamma\)
\(\therefore \gamma=\alpha-\beta \)
\( \tan \gamma =\tan (\alpha-\beta) \)
\( =\frac{\tan \alpha-\tan \beta}{1+\tan \alpha \cdot \tan \beta}\)
\(=\frac{\tan \alpha-\tan \beta}{1+\tan \alpha \cdot \tan \left(\frac{\pi}{2}-\alpha\right)} \cdots[\alpha+\beta=\frac{\pi}{2} \)
\( \therefore \beta=\frac{\pi}{2}-\alpha] \)
\( =\frac{\tan \alpha-\tan \beta}{1+\tan \alpha \cot \alpha} \)
\( =\frac{\tan \alpha-\tan \beta}{2}\)
\(\Rightarrow 2 \tan \gamma=\tan \alpha-\tan \beta\)
\(\Rightarrow \tan \alpha=2 \tan \gamma+\tan \beta\)