CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
    If from a point P (a, b, c) perpendiculars PA, PB are drawn to yz and zx planes, then the equation of the plane OAB is

    A)  \[bcx+cay+abz=0\]

    B)  \[bcx+cay-abz=0\]

    C)  \[bcx-cay+abz=0\]

    D)  \[-bcx+cay+abz=0\]

    E)  \[ax+by+cz=0\]

    Correct Answer: B

    Solution :

    PA, PB are perpendiculars drawn from P(a, b, c) on\[yz\]and\[zx-\]planes. \[\therefore \] A(0, b, c) and B (a, 0, c) are points on\[yz\]and \[zx-\]planes. The equation of plane passing through (0, 0, 0) is \[Ax+By+Cz=0\] Which also passes through A and B. \[\therefore \]  \[A.0+B.b+C.c=0\]                 ...(i) and        \[A.a+B.O+C.c=0\]                 ...(ii) On solving Eqs. (i) and (ii), we get \[\frac{A}{bc-0}=\frac{B}{ac-0}=\frac{C}{0-ab}=\lambda (say)\] \[\Rightarrow \]               \[A=\lambda bc,B=\lambda ac,C=-\lambda ab\] \[\therefore \]Required equation is \[bcx+acy-abz=0\]


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