JEE Main & Advanced JEE Main Paper (Held On 26 May 2012)

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\frac{\sin \left( \pi {{\cos }^{2}}x \right)}{{{x}^{2}}}\] equals.   JEE Main Online Paper (Held On 26-May-2012)  

    A) \[-\pi \]                               

    B)                        1

    C)                        \[-1\]                                    

    D)                        \[\pi \]

    Correct Answer: D

    Solution :

                    Consider\[\underset{x\to 0}{\mathop{\lim }}\,\frac{\sin \left( \pi {{\cos }^{2}}x \right)}{{{x}^{2}}}\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{\sin \left( \pi -\pi {{\sin }^{2}}x \right)}{{{x}^{2}}}\] \[\left[ \because \sin \left( \pi -\theta  \right)=\sin \theta  \right]\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{\sin \left( \pi {{\sin }^{2}}x \right)}{\pi {{\sin }^{2}}x}\times \frac{\left( \pi {{\sin }^{2}}x \right)}{{{x}^{2}}}=\pi \]


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