Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
If the lines given by $\bar{r}=2 \hat{\imath}+\lambda(\hat{\imath}+2 \hat{\jmath}+m \hat{k})$ and $\bar{r}=\hat{\imath}+\mu(2 \hat{\imath}+\hat{\jmath}+6 \hat{k})$ are
perpendicular, then the value of $m$ is
MathematicsThree Dimensional GeometryMHT CETMHT CET 2020 (14 Oct Shift 1)
Options:
  • A $\frac{3}{2}$
  • B $\frac{-3}{2}$
  • C $\frac{2}{3}$
  • D $\frac{-2}{3}$
Solution:
1367 Upvotes Verified Answer
The correct answer is: $\frac{-2}{3}$
Given lines are $\perp$ er and their d.r.s. are $(1,2, \mathrm{~m})$ and $(2,1,6)$
$\therefore \quad 1(2)+2(1)+m(6)=0$
$\therefore \quad 6 m=-4 \quad \Rightarrow m=\frac{-2}{3}$

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.