If the line $\frac{2-x}{3}=\frac{3 y-2}{4 \lambda+1}=4-z$ makes a right angle with the line $\frac{x+3}{3…

If the line $\frac{2-x}{3}=\frac{3 y-2}{4 \lambda+1}=4-z$ makes a right angle with the line $\frac{x+3}{3 \mu}=\frac{1-2 y}{6}=\frac{5-z}{7}$, then $4 \lambda+9 \mu$ is equal to :
  1. 4
  2. 13
  3. 5
  4. 6

Solution

$\frac{2-x}{3}=\frac{3 y-2}{4 \lambda+1}=4-z...(1)$ $\frac{x-2}{(-3)}=\frac{y-\frac{2}{3}}{\left(\frac{4 \lambda+1}{3}\right)}=\frac{z-4}{(-1)}$ $\begin{aligned} & \frac{x+3}{3 \mu}=\frac{1-2 y}{6}=\frac{5-z}{7}...(2) \\ & \frac{x+3}{3 \mu}=\frac{y-\frac{1}{2}}{(-3)}=\frac{z-5}{(-7)} \\ & \text { Right angle } \Rightarrow(-3)(3 \mu)+\left(\frac{4 \lambda+1}{3}\right)(-3)+(-1)(-7)=0 \\ & -9 \mu-4 \lambda-1+7=0 \\ & 4 \lambda+9 \mu=6\end{aligned}$

Asked in: JEE Main 2024 (05 Apr Shift 1)

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