J & K CET Engineering J and K - CET Engineering Solved Paper-2014

  • question_answer
    If \[\sin y=x\sin (a+y),\] then find \[dy/dx\].

    A)  \[{{\sin }^{2}}\,(a+y)/\sin a\]

    B)  \[\sin a/{{\sin }^{2}}\,(a+y)\]

    C)  \[\sin a/{{\sin }^{2}}\,(a-y)\]

    D)  \[{{\sin }^{2}}(a-y)\sin a\]

    Correct Answer: A

    Solution :

     Given,  \[\sin y=x\sin (a+y)\] \[\Rightarrow \] \[x=\frac{\sin y}{\sin (a+y)}\] On differentiating w. r. to x, we get \[1=\frac{\sin (a+y).cosy\frac{dy}{dx}-\sin y\cos (a+y)\frac{dy}{dx}}{{{\sin }^{2}}\,(a+y)}\] \[\Rightarrow \] \[1=\frac{\frac{dy}{dx}.\sin (a+y-y)}{{{\sin }^{2}}(a+y)}\] \[\Rightarrow \] \[\frac{dy}{dx}=\frac{{{\sin }^{2}}(a+y)}{\sin a}\]


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