10th Class Mathematics Introduction to Trigonometry Question Bank MCQs - Introduction to Trigonometry

  • question_answer
    If \[\sin \alpha =\frac{1}{2}\] and \[\tan \beta =\frac{1}{\sqrt{3}},\] \[\alpha >0{}^\circ ,\] \[\beta >0{}^\circ \] then the value of \[\cot \,(\alpha +\beta )\] is: (CBSE 2017)

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

    B) \[\sqrt{3}\]

    C) \[1\]

    D) \[0\]

    Correct Answer: A

    Solution :

    [a] Given, \[\sin \alpha =\frac{1}{2}=\sin 30{}^\circ \]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\alpha =30{}^\circ \]
    and\[\tan \beta =\frac{1}{\sqrt{3}}=\tan 30{}^\circ \]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\beta =30{}^\circ \]
    \[\therefore \,\,\,\,\,\,\,\,\,\,\,\,\cot (\alpha +\beta )=\cot (30{}^\circ +30{}^\circ )=\cot 60{}^\circ =\frac{1}{\sqrt{3}}\]


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