Differentiation Question 293

Question: If $ y={\log _{\sin x}}(\tan x), $ then $ {{( \frac{dy}{dx} )} _{\pi /4}}= $

Options:

A) $ \frac{4}{\log 2} $

B) $ -4\log 2 $

C) $ \frac{-4}{\log 2} $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

$ y=\frac{\log \tan x}{\log \sin x} $

Therefore $ \frac{dy}{dx}=\frac{(\log \sin x)( \frac{{{\sec }^{2}}x}{\tan x} )-(\log \tan x)(\cot x)}{{{(\log \sin x)}^{2}}} $

Therefore $ {{( \frac{dy}{dx} )} _{\pi /4}}=\frac{-4}{\log 2} $ (On simplification).