JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Fundamental trigonometrical ratios and functions, Trigonometrical ratio of allied angles

  • question_answer
    \[\frac{2\sin \theta \,\tan \theta (1-\tan \theta )+2\sin \theta {{\sec }^{2}}\theta }{{{(1+\tan \theta )}^{2}}}=\] [Roorkee 1975]

    A) \[\frac{\sin \,\theta }{1+\tan \theta }\]

    B) \[\frac{2\,\sin \theta }{1+\tan \theta }\]

    C) \[\frac{2\sin \theta }{{{(1+\tan \theta )}^{2}}}\]

    D) None of these

    Correct Answer: B

    Solution :

    Given expression \[=\frac{2\,\sin \theta }{{{(1+\tan \,\theta )}^{2}}}\,\left\{ \tan \,\theta \,(1-\tan \,\theta )+{{\sec }^{2}}\theta  \right\}\] \[=\frac{2\,\sin \theta }{{{(1+\tan \,\theta )}^{2}}}\,\left\{ \tan \,\theta \,-{{\tan }^{2}}\,\theta +1+{{\tan }^{2}}\theta  \right\}\]\[=\frac{2\,\sin \theta }{1+\tan \theta }\].


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