KVPY Sample Paper KVPY Stream-SX Model Paper-31

  • question_answer
    \[\int{\frac{\sin \frac{5x}{2}}{\sin \frac{x}{2}}}dx\] is equal to

    A) \[x+2\sin x+\sin 2x+C\]

    B) \[x+2\cos x+\sin 2x+C\]

    C) \[x-2\sin x+\sin 2x+C\]

    D) \[x+2\sin x-\sin 2x+C\]

    Correct Answer: A

    Solution :

    \[\int{\frac{\sin \frac{5x}{2}}{\sin \frac{x}{2}}}dx=\int{\frac{2\sin \frac{5x}{2}\cos \frac{x}{2}}{2\sin \frac{x}{2}\cos \frac{x}{2}}}dx\]
    \[=\int{\left( \frac{\sin 3x+\sin 2x}{\sin x} \right)}dx\]
    \[=\int{2\cos xdx+\int{(3-4si{{n}^{2}}x)}}dx\]
    \[=2\int{\cos xdx+\int{dx+2}}\int{\cos 2xdx}\]
    \[=2\sin x+x+\sin 2x+C.\]


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