JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2007

  • question_answer
        The normal to the curve\[x=a(1+cos\theta \text{)},\] \[y=a\sin \theta \]at\[\theta \]always passes through the fixed point

    A)  \[(a,\text{ }0)\]               

    B) \[(0,\text{ }a)\]

    C)  (0, 0)                                    

    D) \[(a,\text{ }a)\]

    Correct Answer: A

    Solution :

                    We have, \[x=a(1+\cos \theta ),y=a\sin \theta \] \[\frac{dx}{d\theta }=a(-\sin \theta ),\frac{dy}{d\theta }=a\cos \theta \] \[\Rightarrow \] \[\frac{dy}{dx}=\frac{dy/d\theta }{dx/d\theta }=-\frac{\cos \theta }{\sin \theta }\] \[\therefore \]Equation of normal at\[[a(1+\cos \theta ).a\sin \theta ]\] \[(y-a\sin \theta )=\frac{\sin \theta }{\cos \theta }[x-a(1+\cos \theta )]\] It is clear that in the given options normal passes through the point (a, 0).


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