The d.r.s. of the normal to the plane passing through the origin and the line of intersection of the planes…

The d.r.s. of the normal to the plane passing through the origin and the line of intersection of the planes $x+2 y+3 z=4$ and $4 x+3 y+2 z=1$ are
  1. 3,2,1
  2. 2,3,1
  3. 1,2,1
  4. 3,1,2

Solution

Equation of the plane passing through the line of intersection of the given planes, is $(x z+2 y+3 z-4)+\lambda(4 x+3 y+2 z-1)=0$ Since the plane (1) passes through origin, We get $-4-\lambda=0 \quad \Rightarrow \lambda=-4$ Substituting value of $\lambda$ in equation (1), we get $\begin{aligned} & -15 x-10 y-5 z=0 \quad \Rightarrow 3 x+2 y+z=0 \\ & \therefore \text { d.r.s. are }(3,2,1) \end{aligned}$

Asked in: MHT CET 2021 (22 Sep Shift 2)

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