MCQ
The $\mathop {\lim }\limits_{x \to 0} {(\cos x)^{\cot x}}$ is
  • A
    $-1$
  • B
    $0$
  • $1$
  • D
    None of these

Answer

Correct option: C.
$1$
c
(c) $y = \mathop {\lim }\limits_{x \to 0} {(\cos x)^{\cot x}}$

Taking $log$ on both sides,

==> $\log y = \mathop {\lim }\limits_{x \to 0} \,\,\cot x\log \cos x$

==> $\log y = \mathop {\lim }\limits_{x \to 0} \frac{{\log \cos x}}{{\tan x}}$,$\left( {\frac{0}{0} \,\, {\rm{form}}} \right)$

Applying $L-$ Hospital’s rule,

==> $\log y = \mathop {\lim }\limits_{x \to 0} \frac{{ - \tan x}}{{{{\sec }^2}x}}$= 0

==> $y = {e^0}$ ==> $y = 1$.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free