Manipal Engineering Manipal Engineering Solved Paper-2009

  • question_answer
    \[\int{\left( \frac{2-\sin 2x}{1-\cos 2x} \right)}\,{{e}^{x}}\]is equal to

    A) \[-{{e}^{x}}\cot x+c\]                    

    B) \[{{e}^{x}}\cot x+c\]

    C) \[2{{e}^{x}}\cot x+c\]   

    D)        \[-2{{e}^{x}}+\cot x+c\]

    Correct Answer: A

    Solution :

    Let \[I=\int_{{}}^{{}}{\left( \frac{2-\sin 2x}{1-\cos \,2x} \right)\,{{e}^{x}}dx}\] \[I=\int_{{}}^{{}}{\left( \frac{2-2\sin x\cos x}{2{{\sin }^{2}}x} \right){{e}^{x}}dx}\] \[=\int_{{}}^{{}}{\underset{II}{\mathop{{{\operatorname{cosec}}^{2}}}}\,x\underset{I}{\mathop{{{e}^{x}}}}\,dx-\int_{{}}^{{}}{\cot \,x\,{{e}^{x}}dx}}\] \[=-\cot \,x\,{{e}^{x}}-\int_{{}}^{{}}{(-\cos \,x){{e}^{x}}\,dx}\]                                 \[-\int_{{}}^{{}}{\cot \,x{{e}^{x}}\,dx\,+c}\] \[=-\cot \,x\,{{e}^{x}}\,+c\]


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