`lim_(xto0) (1)/(x)cos^(1)((1-x^(2))/(1+x^2))` is equal to
A. `f(x)f(y)`
B. `f(x)+f(y)`
C. `f(x)-f(y)`
D. none of these

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1 Answers

Correct Answer - D
We know that `cos^(-1)((1-x^(2))/(1+x^2))={{:(2tan^(-1)x", "xge0),(-2tan^(-1)x", "xle0):}`
or `underset(xto0)lim(1)/(x)cos^(-1)((1-x^(2))/(1+x^2))=underset(xto0^(+))lim(2tan^(-1)x)/(x)=2`
and`underset(xto0)lim(1)/(x)cos^(-1)((1-x^(2))/(1+x^2))=underset(xto0^(-))lim[-(2tan^(-1)x)/(x)]=-2`

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