2. Solved Papers
  3. CET Karnataka Engineering

CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2003

  • question_answer
    If the vectors \[4\hat{i}+11\hat{j}+m\hat{k}\], \[7\hat{i}+2\hat{j}+6\hat{k}\]  and \[i+5j+4k\] arc coplanar then m is equal to :

    A)  0                                            

    B)  38

    C)  -10                                        

    D)  10

    Correct Answer: D

    Solution :

    Let \[\vec{a}=4\hat{i}+11\hat{j}+m\hat{k}\] \[\vec{b}=7\hat{i}+2\hat{j}+6\hat{k}\]                                                 \[\vec{c}=\hat{i}+5\hat{j}+4\hat{k}\] As the \[\vec{a}\text{ }\vec{b}\text{ }\vec{c}\] are coplanar \[\therefore \]  \[\vec{a}.\,\,(\vec{b}\times \vec{c})=0\] \[\Rightarrow \]               \[\left| \begin{matrix}    4 & 11 & m  \\    7 & 2 & 6  \\    1 & 5 & 4  \\ \end{matrix} \right|=0\]              \[\Rightarrow \]               \[33m=330\]                 \[m=10\]


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