Integral Calculus Question 429

Question: $ \int_{{}}^{{}}{\frac{cose{c^{2}}x}{1+\cot x}dx=} $

[MNR 1973]

Options:

A) $ \log (1+\cot x)+c $

B) $ -\log (1+\cot x)+c $

C) $ \frac{1}{2{{(1+\cot x)}^{2}}}+c $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

Put $ 1+\cot x=t\Rightarrow cose{c^{2}}x,dx=-dt, $ then $ \int_{{}}^{{}}{\frac{cose{c^{2}}x}{1+\cot x},dx}=-\int_{{}}^{{}}{\frac{1}{t},dt=-\log t+c}=-\log (1+\cot x)+c $ .