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

  • question_answer
    The value of \[\frac{\sin 60{}^\circ +\cot 45{}^\circ -\text{cosec 30}{}^\circ }{\sec 60{}^\circ -\cos 30{}^\circ +\tan 45{}^\circ }\] is:

    A) \[\frac{4\sqrt{3}-9}{33}\]

    B) \[\frac{4\sqrt{3}+9}{33}\]

    C) \[\frac{9\sqrt{3}-4}{33}\]

    D) \[\frac{9\sqrt{3}+4}{33}\]

    Correct Answer: A

    Solution :

    [a] We have,  \[\frac{\sin 60{}^\circ +\cot 45{}^\circ -\cos ec\,\,30{}^\circ }{\sec 60{}^\circ -\cos 30{}^\circ +\tan 45{}^\circ }\]
    \[=\frac{\frac{\sqrt{3}}{2}+1-2}{2-\frac{\sqrt{3}}{2}+1}=\frac{\frac{\sqrt{3}+2-4}{2}}{\frac{4-\sqrt{3}+2}{2}}=\frac{\sqrt{3}-2}{6-\sqrt{3}}\]
    \[=\frac{\sqrt{3}-2}{6-\sqrt{3}}\times \frac{6+\sqrt{3}}{6+\sqrt{3}}=\frac{(\sqrt{3}-2)\,\,(6+\sqrt{3})}{{{6}^{2}}-{{(\sqrt{3})}^{2}}}\]
    \[=\frac{6\sqrt{3}+3-12-2\sqrt{3}}{36-3}=\frac{4\sqrt{3}-9}{33}\]


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