Functions Question 249

Question: $ \underset{x\to 0}{\mathop{\lim }},\frac{\sin (\pi {{\cos }^{2}}x)}{x^{2}}= $

[IIT Screening 2001;UPSEAT 2001; MP PET 2002]

Options:

A) $ (-1,1) $

B) $ \pi $

C) $ \pi /2 $

D) 1

Show Answer

Answer:

Correct Answer: B

Solution:

Limit $ =\underset{x\to 0}{\mathop{lim}}( \frac{\cos (\pi {{\cos }^{2}}x).\pi .2\cos x(-\sin x)}{2x} ) $ $ =\underset{x\to 0}{\mathop{lim}},\pi \cos (\pi {{\cos }^{2}}x).\cos x.( \frac{-\sin x}{x} ) $ $ =\pi (-1).1.(-1)=\pi $ .