JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Trigonometrical ratios of multiple and sub multiple angles

  • question_answer
    \[\sqrt{\frac{1-\sin A}{1+\sin A}}=\]

    A) \[\sec A+\tan A\]

    B) \[\tan \left( \frac{\pi }{4}-A \right)\]

    C) \[\tan \left( \frac{\pi }{4}+\frac{A}{2} \right)\]

    D) \[\tan \left( \frac{\pi }{4}-\frac{A}{2} \right)\]

    Correct Answer: D

    Solution :

    \[\sqrt{\frac{1-\sin A}{1+\sin A}}=\sqrt{\frac{1-\cos \left( \frac{\pi }{2}-A \right)}{1+\cos \left( \frac{\pi }{2}-A \right)}}\] \[=\sqrt{\frac{2{{\sin }^{2}}\left( \frac{\pi }{4}-\frac{A}{2} \right)}{2{{\cos }^{2}}\left( \frac{\pi }{4}-\frac{A}{2} \right)}}=\tan \left( \frac{\pi }{4}-\frac{A}{2} \right)\].


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