The line $\frac{x-1}{3}=\frac{y+1}{2}=\frac{z-1}{5}$ and $\frac{x+2}{4}=\frac{y-1}{3}=\frac{z+1}{-2}$

The line $\frac{x-1}{3}=\frac{y+1}{2}=\frac{z-1}{5}$ and $\frac{x+2}{4}=\frac{y-1}{3}=\frac{z+1}{-2}$
  1. intersect each other and point of intersection is $(4,3,-2)$.
  2. do not intersect.
  3. intersect each other and point of intersection is $(3,2,5)$.
  4. intersect each other and point of intersection is $(-2,-1,-1)$

Solution

$\begin{aligned} & \text { S.D. }=\left|\frac{\left|\begin{array}{ccc} 1+2 & -1-1 & 1+1 \\ 3 & 2 & 5 \\ 4 & 3 & -2 \end{array}\right|}{\sqrt{(-4-15)^2+(20+6)^2+(9-8)^2}}\right| \\ & =\left|\frac{3(-4-15)-2(20+6)+2(9-8)}{\sqrt{19^2+26^2+1^2}}\right| \\ & =\frac{|-57-52+2|}{\sqrt{361+676+1}}=\frac{107}{\sqrt{1039}} \neq 0 \end{aligned}$ Hence, the two lines do not intersect each other.

Asked in: MHT CET 2022 (08 Aug Shift 2)

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