Q56 / 160 · WBJEE 2011 · Mathematics

If \(\theta+\phi=\frac{\pi}{4}\), then \((1+\tan \theta)(1+\tan \phi)\) is equal to

  • A
    1
  • Correct answer
    B
    2
  • C
    \(5 / 2\)
  • D
    \(1 / 3\)

Solution

\(\begin{aligned} & \text { Hints: }(1+\tan \theta)\left(1+\frac{(1-\tan \theta)}{1+\tan \theta}\right) \\ & =(1+\tan \theta) \frac{2}{1+\tan \theta}=2 \end{aligned}\)

Hence, the correct answer is option: 'B'.

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