A) 8
B) 0
C) ? 2
D) 6
Correct Answer: C
Solution :
Let four points \[A,B,C,D\]represent the given points So, \[\overrightarrow{AB}=-\mathbf{i}-\mathbf{j}+4\mathbf{k},\,\,\overrightarrow{BC}=2\mathbf{i}+2\mathbf{j}-5\mathbf{k},\] \[\overrightarrow{CD}=-2\mathbf{i}-(\lambda +4)\mathbf{j}+3\mathbf{k}\] From the condition, \[[\overrightarrow{AB}\,\,\overrightarrow{BC}\,\,\overrightarrow{CD}]=0\] Þ \[\left| \,\begin{matrix} -1 & -1 & 4 \\ 2 & 2 & -5 \\ -2 & -(\lambda +4) & 3 \\ \end{matrix}\, \right|=0\] Þ \[-1[2.3-5(\lambda +4)]+1[6-10]+4[-2(\lambda +4)+4]=0\] \[\Rightarrow \lambda =-2\].You need to login to perform this action.
You will be redirected in
3 sec