Differentiation Question 1

Question: $ \frac{d}{dx}(\log \tan x)= $

[MNR 1986]

Options:

A) $ 2\sec 2x $

B) $ 2\text{cosec }2x $

C) $ \sec 2x $

D) $ cosec2x $

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Answer:

Correct Answer: B

Solution:

$ \frac{d}{dx}(\log \tan x)=\frac{1}{\tan x}{{\sec }^{2}}x=\frac{\cos x}{{{\cos }^{2}}x\sin x} $

$ =\frac{2}{2}\frac{1}{\cos x\sin x}=2cosec2x $ .