VIT Engineering VIT Engineering Solved Paper-2009

  • question_answer
    \[\int{\left( \frac{2-\sin 2x}{1-\cos 2x} \right)}\,\,{{e}^{x}}dx\] 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 \[I=\int{\left( \frac{2-\sin 2x}{1-\cos 2x} \right)}\,{{e}^{x}}dx\]    \[=\int{\left( \frac{2-\sin 2x\,\cos x}{2\,{{\sin }^{2}}x} \right)}\,{{e}^{x}}dx\]    \[=\int{\underset{\text{II}}{\mathop{\text{cose}{{\text{c}}^{2}}x}}\,\,\underset{\text{I}}{\mathop{{{e}^{x}}}}\,dx}-\int{\cot x\,{{e}^{x}}}dx\]    \[=-\cot x\,{{e}^{x}}-\int{(-cot\,x)\,{{e}^{x}}dx}\]       \[-\int{\cot x\,{{e}^{x}}}dx+c\]    \[=-\cot x\,{{e}^{x}}+c\]


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