JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2011

  • question_answer
        If the lines joining the origin to the intersection of the line\[y=mx+2\]and the curve\[{{x}^{2}}+{{y}^{2}}=1\] are at right angles, then

    A)  \[{{m}^{2}}=1\]               

    B)  \[{{m}^{2}}=3\]

    C)  \[{{m}^{2}}=7\]               

    D)  \[2{{m}^{2}}=1\]

    Correct Answer: C

    Solution :

                    Joint equation of the lines joining the origin and the point of intersection of the line \[y=mx+2\]and the curve\[{{x}^{2}}+{{y}^{2}}=1\]is \[{{x}^{2}}+{{y}^{2}}={{\left( \frac{y-mx}{2} \right)}^{2}}\] \[\Rightarrow \]               \[{{x}^{2}}(4-{{m}^{2}})+2mxy+3{{y}^{2}}=0\] Since, lines are at right angles. \[\therefore \]  \[4-{{m}^{2}}+3=0\] \[\Rightarrow \]               \[{{m}^{2}}=7\]


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