RAJASTHAN ­ PET Rajasthan PET Solved Paper-2001

  • question_answer
    \[\underset{x\to 0}{\mathop{\lim }}\,\frac{\sqrt{\frac{1-\cos 2x}{2}}}{x}\]is equal to

    A)  1             

    B)  \[-1\]

    C)  0                

    D)  None of these

    Correct Answer: D

    Solution :

     \[\underset{x\to 0}{\mathop{\lim }}\,\sqrt{\frac{\frac{1-\cos 2x}{2}}{x}}\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{\sqrt{\frac{1-1+2{{\sin }^{2}}x}{2}}}{x}\] \[=\underset{x\to 0}{\mathop{\lim }}\,\frac{|\sin x|}{x}\] \[LHL=\underset{x\to 0}{\mathop{\lim }}\,-\frac{\sin x}{x}=-1\] and  \[RHL=\underset{x\to 0}{\mathop{\lim }}\,\frac{\sin x}{x}=1\] Hence, limit does not exist.


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