Integral Calculus Question 273

Question: $ \int_{{}}^{{}}{\frac{cosec\theta -\cot \theta }{cosec\theta +\cot \theta }}\ d\theta = $

Options:

A) $ 2cosec\theta -2\cot \theta -\theta +c $

B) $ 2,cosec\theta -2\cot \theta +\theta +c $

C) $ 2,cosec\theta +2\cot \theta -\theta +c $

D) None of these

Show Answer

Answer:

Correct Answer: A

Solution:

$ \int_{{}}^{{}}{\frac{cosec\theta -\cot \theta }{cosec\theta +\cot \theta },d\theta }=\int_{{}}^{{}}{{{(cosec\theta -\cot \theta )}^{2}}d\theta } $ $ =\int_{{}}^{{}}{cose{c^{2}}\theta ,d\theta }+\int_{{}}^{{}}{{{\cot }^{2}}\theta ,d\theta }-2\int_{{}}^{{}}{cosec\theta \cot \theta ,d\theta } $ $ =\int_{{}}^{{}}{(2cose{c^{2}}\theta -1),d\theta }-2\int_{{}}^{{}}{cosec\theta \cot \theta ,d\theta } $ $ =2cosec\theta -2\cot \theta -\theta +c. $