JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Fundamental Integration

  • question_answer
    \[\int_{{}}^{{}}{\frac{\text{cosec}\theta -\cot \theta }{\text{cosec}\theta +\cot \theta }}\ d\theta =\]

    A)            \[2\text{cosec}\theta -2\cot \theta -\theta +c\]                        

    B)            \[2\,\text{cosec}\theta -2\cot \theta +\theta +c\]

    C)            \[2\,\text{cosec}\theta +2\cot \theta -\theta +c\]

    D)            None of these

    Correct Answer: A

    Solution :

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


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