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

  • question_answer
    In a \[\Delta ABC\], \[b=2,C={{60}^{o}},c=\sqrt{6}\], then a =

    A) \[\sqrt{3}-1\]

    B) \[\sqrt{3}\]

    C) \[\sqrt{3}+1\]

    D) None of these

    Correct Answer: C

    Solution :

    We have \[\frac{b}{\sin B}=\frac{c}{\sin C}\]Þ \[\sin B=\frac{b\sin C}{c}\] Þ \[\sin B=\frac{2\sin {{60}^{o}}}{\sqrt{6}}=\frac{2}{\sqrt{6}}.\frac{\sqrt{3}}{2}=\frac{1}{\sqrt{2}}\]Þ\[B={{45}^{o}}\],\[(\because B\ne {{135}^{o}})\] \ \[A={{180}^{o}}-(B+C)={{75}^{o}}\] Now\[\frac{\sin A}{a}=\frac{\sin B}{b}\]Þ\[a=\frac{b\sin A}{\sin B}=\frac{2\sin {{75}^{o}}}{\sin {{45}^{o}}}=\sqrt{3}+1\].


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