CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2009

  • question_answer
    \[\int{\frac{\cos x-\sin x}{1+2\sin x\cos x}}dx\]is equal to

    A)  \[-\frac{1}{\cos x-\sin x}+c\]

    B)  \[\frac{\cos x+\sin x}{\cos x-\sin x}+c\]

    C)  \[-\frac{1}{\sin x+\cos x}+c\]

    D)  \[\frac{x}{\sin x+\cos x}+c\]

    E)  \[\tan x+\sec x+c\]

    Correct Answer: C

    Solution :

    Let\[I=\int{\frac{\cos x-\sin x}{{{(\cos x+\sin x)}^{2}}}}dx\] Put         \[\cos x+\sin x=t\] \[\Rightarrow \]               \[(\cos x-\sin x)dx=dt\] \[\therefore \]  \[I=\int{\frac{1}{{{t}^{2}}}}dt\]                 \[I=-\frac{1}{t}+c=\frac{1}{\sin x+\cos x}+c\]


You need to login to perform this action.
You will be redirected in 3 sec spinner