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

  • question_answer
    If  in a triangle \[ABC\], \[2\cos A=\sin B\,\text{cosec}\,C,\] then [MP PET 1996]

    A) \[a=b\]

    B) \[b=c\]

    C) \[c=a\]

    D) \[2a=bc\]

    Correct Answer: C

    Solution :

    \[2\cos A=\frac{\sin B}{\sin C}\Rightarrow \frac{2({{c}^{2}}+{{b}^{2}}-{{a}^{2}})}{2bc}=\frac{b}{c}\] \[\Rightarrow \] \[{{c}^{2}}={{a}^{2}}\Rightarrow \] \[=\pi {{R}^{2}}=4\pi \].


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