Differentiation Question 233

Question: $ \frac{d}{dx}( \frac{\sec x+\tan x}{\sec x-\tan x} )= $

[DSSE 1979, 81; CBSE 1981]

Options:

A) $ \frac{2\cos x}{{{(1-\sin x)}^{2}}} $

B) $ \frac{\cos x}{{{(1-\sin x)}^{2}}} $

C) $ \frac{2\cos x}{1-\sin x} $

D) None of these

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Answer:

Correct Answer: A

Solution:

$ \frac{d}{dx}( \frac{\sec x+\tan x}{\sec x-\tan x} )=\frac{d}{dx}( \frac{1+\sin x}{1-\sin x} ) $ .