CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2006

  • question_answer
    The   direction   cosines   of   the   line\[4x-4=1-3y=2z-1\]are:

    A)  \[\frac{3}{\sqrt{56}},\frac{-4}{\sqrt{56}},\frac{6}{\sqrt{56}}\]

    B)  \[\frac{3}{\sqrt{29}},\frac{-4}{\sqrt{29}},\frac{6}{\sqrt{29}}\]

    C)  \[\frac{3}{\sqrt{61}},\frac{-4}{\sqrt{61}},\frac{6}{\sqrt{61}}\]

    D)  \[4,-3,2\]

    E)  \[\frac{4}{\sqrt{29}},\frac{-3}{\sqrt{29}},\frac{2}{\sqrt{29}}\]

    Correct Answer: C

    Solution :

    \[4x-4=1-3y=2z-1\] \[\Rightarrow \]               \[\frac{x-1}{\frac{1}{4}}=\frac{y-\frac{1}{3}}{-\frac{1}{3}}=\frac{z-\frac{1}{2}}{\frac{1}{2}}\] \[\therefore \]Direction cosines are \[\frac{\frac{1}{4}}{\sqrt{\frac{1}{16}+\frac{1}{9}+\frac{1}{4}}},\frac{-\frac{1}{3}}{\sqrt{\frac{1}{16}+\frac{1}{9}+\frac{1}{4}}},\frac{\frac{1}{2}}{\sqrt{\frac{1}{16}+\frac{1}{9}+\frac{1}{4}}}\] \[=\frac{3}{\sqrt{61}},\frac{-4}{\sqrt{61}},\frac{6}{\sqrt{61}}\]


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