Manipal Engineering Manipal Engineering Solved Paper-2015

  • question_answer
    If \[\pi \] is a continuous at \[\pi \]then k is equal to

    A) 0                                             

    B) \[\pi \]

    C) \[\pi \]                 

    D) \[^{\text{235}}\text{U}\]

    Correct Answer: D

    Solution :

    It is given that f (x) is continuous at \[x=\frac{\pi }{2}.\] \[\therefore \]\[k=\underset{x\to \pi /2}{\mathop{\lim }}\,f(x)\] \[\Rightarrow \]\[k=\underset{x\to \pi /2}{\mathop{\lim }}\,\frac{\sin (\cos x)-\cos x}{{{(\pi -2x)}^{3}}}\] \[k=\underset{x\to \pi /2}{\mathop{\lim }}\,\frac{\sin (\cos x)-\cos x}{{{\cos }^{3}}x}\times \frac{{{\sin }^{3}}\left( \frac{\pi }{2}-x \right)}{8\left( \frac{\pi }{2}-x \right)}\] \[\therefore \]\[k=-\frac{1}{6}\times \frac{1}{8}=-\frac{1}{48}\left[ \because \underset{x\to 0}{\mathop{\lim }}\,\frac{\sin x-x}{{{x}^{3}}}=-\frac{1}{6} \right]\]


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