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.
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