CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2004

  • question_answer
    The general solution of the differential equation \[\frac{dy}{dx}+\frac{1+\cos 2y}{1-\cos 2y}=0\] is given by :

    A)  \[\tan y+\cot x=c\]        

    B)  \[\tan y-\cot x=c\]

    C)  \[\tan x-\cot y=c\]         

    D)  \[\tan x+\cot x=c\]

    Correct Answer: B

    Solution :

    We have, \[\frac{d\,y}{d\,x}+\frac{1+\cos 2y}{1-\cos \,2x}=0\] \[\Rightarrow \]               \[\frac{dy}{dx}=-\frac{1+\cos 2y}{1-\cos 2x}=-\frac{1+2{{\cos }^{2}}y-1}{1-(1-2{{\sin }^{2}}x)}\] \[\Rightarrow \]               \[\frac{dy}{dx}=-\frac{2{{\cos }^{2}}y}{2{{\sin }^{2}}x}\] \[\Rightarrow \]               \[\int{{{\sec }^{2}}y\,dy=-}\int{\cos e{{c}^{2}}x\,dx}\] \[\Rightarrow \]               \[\tan y-\cot \,x=c\]


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