MCQ
$\lim _{\theta \rightarrow 0} \frac{e^\theta+e^{-\theta}-2}{\sin ^2 \theta}$ is equal to
  • 1
  • B
    $0$
  • C
    -1
  • D
    $\sqrt{-2}$

Answer

Correct option: A.
1
(A)
$\lim _{\theta \rightarrow 0} \frac{e^\theta+e^{-\theta}-2}{\sin ^2 \theta}=\lim _{\theta \rightarrow 0} \frac{e^\theta+\frac{1}{e^\theta}-2}{\sin ^2 \theta}$
$=\lim _{\theta \rightarrow 0} \frac{\left[e^\theta-1\right]^2}{e^\theta \sin ^2 \theta}$
$=\lim _{\theta \rightarrow 0} \frac{\frac{\left(e^\theta-1\right)^2}{\theta^2}}{e^\theta \cdot \frac{\sin ^2 \theta}{\theta^2}}$
$=\frac{[\log e ]^2}{1}-1$

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