MCQ
$\mathop {\lim }\limits_{x \to 0} {\left( {\frac{{1 + \tan x}}{{1 + \sin x}}} \right)^{{\rm{cosec }}x}}$ is equal to
  • A
    $e$
  • B
    $\frac{1}{e}$
  • $1$
  • D
    None of these

Answer

Correct option: C.
$1$
c
(c) Given limit $ = \mathop {\lim }\limits_{x \to 0} [{(1 + \tan x)^{\cos ec\,x}} \times 1/{(1 + \sin x)^{\cos ec\,x}}]$

$ = \mathop {\lim }\limits_{x \to 0} \,{[{\{ 1 + \tan x)^{\cot \,x}}\} ^{sec\,x}} \times \{ 1/{(1 + \sin x)^{\cos ec\,x}}\} ]$

$ = {e^{\sec \,\,0}}.\frac{1}{e} = e\,.\,\frac{1}{e} = 1.$

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