Differentiation Question 232

Question: $ \frac{d}{dx}\sqrt{{{\sec }^{2}}x+cose{c^{2}}x}= $

[DSSE 1981]

Options:

A) $ 4\cos \text{ec 2}x.\cot 2x $

B) $ -4\cos \text{ec 2}x.\cot 2x $

C) $ -4\cos \text{ec }x.\cot 2x $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

$ \frac{d}{dx}[\sqrt{{{\sec }^{2}}x+cose{c^{2}}x}]=\frac{d}{dx}[ \sqrt{( \frac{1}{{{\cos }^{2}}x}+\frac{1}{{{\sin }^{2}}x} )} ] $

$ =\frac{d}{dx}[2cosec2x]=-4cosec2x\cot 2x $ .