The value of λ for which the lines $\frac{2-x}{3}=\frac{3-4y}{5}=\frac{z-2}{3}$ and $\frac{x-2}{-3}=\frac{2y-4}{3}=\frac{2-z}{λ}$ are perpendicular is: |
-2 2 $\frac{8}{19}$ $\frac{19}{8}$ |
$\frac{19}{8}$ |
The correct answer is Option (4) → $\frac{19}{8}$ A line in the symmetric form, $\frac{x-x_1}{a}=\frac{y-y_1}{b}=\frac{z-z_1}{c}$ and direction vector: $d(a,b,c)$ First line: $\frac{2-x}{3}=\frac{3-4y}{5}=\frac{z-2}{3}$ $⇒\frac{x-2}{-3}=\frac{y-\frac{3}{4}}{-\frac{5}{4}}=\frac{z-2}{3}$ $d_1=\left(-3,-\frac{5}{4},3\right)$ Second line: $\frac{x-2}{-3}=\frac{2y-4}{3}=\frac{2-z}{λ}$ $⇒\frac{x-2}{-3}=\frac{y-2}{\frac{3}{2}}=\frac{z-2}{-λ}$ $d_2=\left(-3,\frac{3}{2},-λ\right)$ $d_1.d_2=0$ $(-3)(-3)+\frac{3}{2}×-\frac{5}{4}-3λ=0$ $⇒3λ=\frac{15}{8}-9=\frac{15-72}{8}$ $⇒λ=\frac{19}{8}$ |