2. Sample Papers
  3. JEE Main & Advanced

JEE Main & Advanced Sample Paper JEE Main Sample Paper-21

  • question_answer
    Locus of the centre of all circles passing through (2,4) and cutting the circle \[{{x}^{2}}+{{y}^{2}}=1\]orthogonally is

    A)  \[4x-8y=11\]                

    B)  \[4x+8y=21\]

    C)  \[8x+4y=21\]              

    D)  \[4x-8y=21\]

    Correct Answer: B

    Solution :

    \[S:{{x}^{2}}+{{y}^{2}}\,+2gx\,+2fy+c=0\]            \[h=-g;\,k=-f\]    \[(2,4)\Rightarrow \,4+16+4g+8f+c=0\] \[4g+8f+20+c=0\]                    ?(1) \[f2g(0)+2f(0)=c-1\] \[\therefore \,\,c=1\]                                ?(2) (1) & (2) gives \[4g+8f+21=0\] \[\Rightarrow \,-4h-8k+21=0\] \[\Rightarrow \,4h+8k=21\]


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