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\lim_{x\rightarrow 0}\frac{\sin \left ( \pi \cos ^{2}x \right )}{x^{2}}   is equal to :

  • Option 1)

    -\pi \;

  • Option 2)

    \pi

  • Option 3)

    \; \frac{\pi }{2}

  • Option 4)

    1

 

Answers (1)

best_answer

As we learnt in

Evalution of Trigonometric limit -

\lim_{x\rightarrow a}\:\frac{sin(x-a)}{x-a}=1

\lim_{x\rightarrow a}\:\frac{tan(x-a)}{x-a}=1

put\:\:\:\:\:x=a+h\:\:\:where\:\:h\rightarrow 0

Then\:it\:comes

\lim_{h\rightarrow 0}\:\:\frac{sinh}{h}=\lim_{h\rightarrow 0}\:\:\frac{tanh}{h}=1

\therefore\:\:\:\lim_{x\rightarrow 0}\:\:\frac{sinx}{x}=1\:\;\;and

\therefore\:\:\:\lim_{x\rightarrow 0}\:\:\frac{tanx}{x}=1

-

 

\lim_{x\rightarrow 0}\:\:\:\frac{\sin (\pi \cos ^{2}x)}{x^{2}}

\lim_{x\rightarrow 0}\:\:\:\frac{\sin (\pi (1-\sin ^{2}x))}{x^{2}}

\lim_{x\rightarrow 0}\:\:\:\frac{\sin (\pi -\pi \sin ^{2}x)}{x^{2}}

\lim_{x\rightarrow 0}\:\:\:\frac{\sin (\pi \sin ^{2}x)}{x^{2}}\:\times \frac{\pi \sin^{2}x}{(\pi \sin^{2}x)}

= \pi

 


Option 1)

-\pi \;

This option is incorrect.

Option 2)

\pi

This option is correct.

Option 3)

\; \frac{\pi }{2}

This option is incorrect.

Option 4)

1

This option is incorrect.

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Aadil

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