Q. $\lim_{x \rightarrow 0}\left\{ \frac{1 + \tan x}{1 + \sin x} \right\}^{cosec\ x}$ is equal to

A) $\frac{1}{e}$
B) 1
C) $e$
D) $e^{2}$
Explanation

(b)
$\lim_{x \rightarrow 0}\left\{ \frac{1 + \tan x}{1 + \sin x} \right\}^{cosec\ x}$
$= \lim_{x \rightarrow 0}\frac{\left\lbrack \left( 1 + \frac{\sin x}{\cos x} \right)^{\frac{\cos x}{\sin x}} \right\rbrack^{1/\cos x}}{\left( 1 + \sin x \right)^{1/\sin x}}$
$= \frac{e^{\lim_{x \rightarrow 0}\ \frac{1}{\cos x}}}{e}$
$= \frac{e}{e} = 1$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.