JEE Main & Advanced Mathematics Trigonometric Equations Question Bank Relation between sides and angles, Solutions of triangles

  • question_answer
    In \[\Delta \,ABC\], \[\frac{\cos \frac{1}{2}(B-C)}{\sin \frac{1}{2}A}=\]   [MP PET 1993; Roorkee 1973]

    A) \[\frac{b-c}{a}\]

    B) \[\frac{b+c}{a}\]

    C) \[\frac{a}{b-c}\]

    D) \[\frac{a}{b+c}\]

    Correct Answer: B

    Solution :

      \[\frac{\cos \frac{B-C}{2}}{\sin \frac{A}{2}}=\frac{\sin \frac{B+C}{2}\cos \frac{B-C}{2}}{\sin \frac{B+C}{2}\sin \frac{A}{2}}=\frac{\sin B+\sin C}{\sin A}=\frac{b+c}{a}\].


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