Q.If \( \tan\theta + \cot\theta = 2 \), then the value of \( \theta \) will be — (a) \(\cfrac{\pi}{2}\) (b) \(\cfrac{\pi}{4}\) (c) \(\pi\) (d) \(\cfrac{\pi}{6}\)
Answer: B
If \( \tan\theta + \cot\theta = 2 \) Then, \( (\tan\theta + \cot\theta)^2 = 2^2 \) So, \( (\tan\theta - \cot\theta)^2 + 4\tan\theta \cdot \cot\theta = 4 \) Therefore, \( (\tan\theta - \cot\theta)^2 + 4 = 4 \) Which gives, \( (\tan\theta - \cot\theta)^2 = 0 \) So, \( \tan\theta - \cot\theta = 0 \) Hence, \( (\tan\theta + \cot\theta) + (\tan\theta - \cot\theta) = 2 + 0 \) That means, \( 2\tan\theta = 2 \) So, \( \tan\theta = 1 = \tan\left(\frac{\pi}{4}\right) \) Therefore, \( \theta = \frac{\pi}{4} \)
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