J & K CET Engineering J and K - CET Engineering Solved Paper-2004

  • question_answer
    The value of \[\underset{x\to \pi /2}{\mathop{\lim }}\,\frac{\cot \,x-\cos x}{{{(\pi -2x)}^{3}}}\]

    A)  \[1\]

    B)  \[\frac{1}{16}\]

    C)  \[16\]

    D)  None of these

    Correct Answer: B

    Solution :

    \[\underset{x\to \pi /2}{\mathop{\lim }}\,\frac{\cot \,x-\,\cos \,x}{{{(\pi -2x)}^{3}}}\] \[=\underset{h\to 0}{\mathop{\lim }}\,\frac{-\tan \,h+\sin \,h}{{{(-2h)}^{3}}}\] \[=\underset{h\to 0}{\mathop{\lim }}\,\frac{\sin \,h(1-\cos \,h)}{\cos \,h\times 8{{h}^{3}}}\] \[=\frac{1}{8}\underset{h\to 0}{\mathop{\lim }}\,\frac{\sin \,h}{h}\times \frac{2\,{{\sin }^{2}}\,h/2}{4{{(h/2)}^{2}}}\times \frac{1}{\cos \,h}\] \[=\frac{1}{16}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner