MCQ
If $f(x) = ({\log _{\cot x}}\tan x){({\log _{\tan x}}\cot x)^{ - 1}},$ then $f'(2) = $
  • A
    $2$
  • $0$
  • C
    ${1 \over 2}$
  • D
    $-2$

Answer

Correct option: B.
$0$
b
(b) Obviously, $f(x) = {({\log _{\cot x}}\tan x)^2}$

$ = {({\log _{\cot x}}{(\cot x)^{ - 1}})^2} \Rightarrow f'(x) = 0$ .

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