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

  • question_answer
    If \[\sqrt{3}\sin \theta =\cos \theta ,\]then value of \[\frac{3{{\cos }^{2}}\theta +2\cos \theta }{3\cos \theta +2}\]is:

    A) \[\sqrt{3}\,\cos \theta \]

    B) \[3\,\cos \theta \]

    C) \[3\,\sin \theta \]

    D) \[\sqrt{3}\,\sin \theta \]

    Correct Answer: D

    Solution :

    [d]\[\frac{3{{\cos }^{2}}\theta +2\cos \theta }{3\cos \theta +2}\]
    \[=\frac{3\times {{(\sqrt{3}\sin \theta )}^{2}}+2\times \sqrt{3}\sin \theta }{3\times \sqrt{3}\sin \theta +2}\]\[(\cos \theta =\sqrt{3}\sin \theta )\]
    \[=\frac{3\times 3{{\sin }^{2}}\theta +2\sqrt{3}\sin \theta }{3\sqrt{3}\sin \theta +2}=\frac{\sqrt{3}\sin \theta (3\sqrt{3}\sin \theta +2)}{(3\sqrt{3}\sin \theta +2)}\]
    \[=\sqrt{3}\sin \theta \]


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