JEE Main & Advanced Mathematics Trigonometric Identities Question Bank Trigonometrical ratios of sum and difference of two and three angles

  • question_answer
    \[\frac{{{\sin }^{2}}A-{{\sin }^{2}}B}{\sin A\cos A-\sin B\cos B}=\] [MP PET 1993]

    A) \[\tan (A-B)\]

    B) \[\tan (A+B)\]

    C) \[\cot (A-B)\]

    D) \[\cot (A+B)\]

    Correct Answer: B

    Solution :

    \[\frac{{{\sin }^{2}}A-{{\sin }^{2}}B}{\sin A\cos A-\sin B\cos B}=\frac{2\,\sin \,(A+B)\,\sin \,(A-B)}{\sin \,2A-\sin \,2B}\] \[=\frac{2\,\sin \,(A+B)\,\sin \,(A-B)}{2\,\cos \,(A+B)\,\sin \,(A-B)}=\tan \,(A+B)\].


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