KVPY Sample Paper KVPY Stream-SX Model Paper-31

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\frac{{{\sin }^{2}}x}{\sqrt{2}-\sqrt{1+\cos x}}=\]

    A) \[\sqrt{2}\]

    B) 2

    C) \[4\]

    D) \[4\sqrt{2}\]

    Correct Answer: D

    Solution :

    \[\underset{x\to 0}{\mathop{\lim }}\,\frac{{{\sin }^{2}}x}{\sqrt{2}-\sqrt{1+\cos x}}\]
    \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{{{\sin }^{2}}x\left( \sqrt{2}+\sqrt{1+\cos x} \right)}{1-\cos x}\]
    \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{{{\sin }^{2}}x}{{{x}^{2}}}\left( \frac{1}{\frac{1-\cos x}{{{x}^{2}}}} \right)\left( \sqrt{2}+\sqrt{1+\cos x} \right)\]
    \[=\frac{2\sqrt{2}}{1/2}=4\sqrt{2}.\]


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