CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    The parametric equations of the circle\[{{x}^{2}}+{{y}^{2}}+x+\sqrt{3}y=0\]are

    A)  \[x=1+\cos \theta ,y=\frac{\sqrt{3}}{2}+\sin \theta \]

    B)  \[x=-\frac{1}{2}+\cos \theta ,y=-\frac{\sqrt{3}}{2}+\sin \theta \]

    C)  \[x=\frac{1}{2}+\cos \theta ,y=-\frac{\sqrt{3}}{2}+\sin \theta \]

    D)  \[x=\frac{1}{2}+\frac{1}{2}+\cos \theta ,y=\frac{\sqrt{3}}{2}+\frac{1}{2}+\sin \theta \]

    E)  \[x=\cos \theta -1,y=\frac{\sqrt{3}}{2}+\sin \theta \]

    Correct Answer: B

    Solution :

    Equation of circle \[{{x}^{2}}+{{y}^{2}}+x+\sqrt{3}y=0\] \[\Rightarrow \]               \[({{x}^{2}}+x)+({{y}^{2}}+\sqrt{3}y)=0\] \[\Rightarrow \]\[\left( {{x}^{2}}+x+\frac{1}{4} \right)+\left( {{y}^{2}}+\sqrt{3}y+\frac{3}{4} \right)=\frac{1}{4}+\frac{3}{4}\]                \[\Rightarrow \]\[{{\left( x+\frac{1}{2} \right)}^{2}}+{{\left( y+\frac{\sqrt{3}}{2} \right)}^{2}}=1\] \[\Rightarrow \]\[{{\left( x-\left( \frac{-1}{2} \right) \right)}^{2}}+{{\left( y-\left( \frac{-\sqrt{3}}{2} \right) \right)}^{2}}=1\] Let          \[x+\frac{1}{2}\cos \theta \Rightarrow x=-\frac{1}{2}+\cos \theta \]        and\[y+\frac{\sqrt{3}}{2}=\sin \theta \Rightarrow y=\frac{-\sqrt{3}}{2}+\sin \theta \] Which are the required parametric coordinates of the given circle.


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