CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    The   lines\[r=i+j-k+\lambda (3i-j)\]and\[r=4i-k+\mu (2i+3k)\]intersect at the point

    A)  (0, 0, 0)               

    B)         (0, 0, 1)

    C)  (0, - 4, -1)       

    D)         (4, 0, -1)

    E)  (4, 1, -1)

    Correct Answer: D

    Solution :

    The given lines,\[r=(i+j-k)+\lambda (3i-j)\] ...(i) and \[r=(4i-k)+\mu (2i+3k)\]                ...(ii) From Eqs. (i) and (ii), \[(i+j-k)+\lambda (3i-j)\]                 \[=(4i-k)+\mu (2i+3k)\] \[(1+3\lambda )i+(1-\lambda )j-k\]                 \[=(4+2\mu )i+0j+(-1+3\mu )k\] Equating the coefficient of\[i,\text{ }j\]and k on both sides,                 \[1+3\kappa =4+2\mu \]                 \[3\lambda -2\mu =3\]                 \[1-\lambda =0\] \[\Rightarrow \]               \[\lambda =1\]                 \[-1+3\mu =-1\] \[\Rightarrow \]               \[\mu =0\] On putting these values in Eq. (i),                 \[r=(i+j-k)+(3i-j)\] \[r=4i+0j-k\] So, the intersection point is\[(4,0,-1)\].


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