CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2005

  • question_answer
    Solution of the differential equation \[\frac{dy}{dx}\tan y=\sin (x+y)+\sin (x-y)\]is:

    A)  \[sec\text{ }y+2\text{ }cos\text{ }x=c\]

    B)  \[sec\text{ }y-2\text{ }cos\text{ }x=c\]

    C)  \[cos\text{ }y-2\text{ }sin\text{ }x=c\]

    D)  \[tan\text{ }y-2\text{ }sec\text{ }y=c\]

    E)  \[sec\text{ }y+2\text{ }sin\text{ }x=c\]

    Correct Answer: A

    Solution :

    \[\because \]\[\frac{dy}{dx}\tan y=\sin (x+y)+\sin (x-y)\] \[\Rightarrow \]               \[\frac{dy}{dx}\tan y=2\sin x\,\cos y\] \[\Rightarrow \]               \[\int{\tan y\,\sec y\,dy}=2\int{\sin x\,dx}\] \[\Rightarrow \]               \[\sec y+2\cos x=c\]


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