The distance of the point $(3,4,5)$ from the point of intersection of the line…

The distance of the point $(3,4,5)$ from the point of intersection of the line $\frac{x-3}{1}=\frac{y-4}{2}=\frac{z-5}{2}$ and plane $x+y+z=2$ is
  1. 6 units
  2. 13 units
  3. 10 units
  4. 7 units

Solution

Given $\frac{x-3}{1}=\frac{y-4}{2}=\frac{z-5}{2}=\lambda \quad \ldots$ (say) ...(1) Hence coordinates of any point on this line are $\therefore x=\lambda+3, y=2 \lambda+4, z=2 \lambda+5$ Since this point lies on the plane, we write $\begin{array}{l} (\lambda+3)+(2 \lambda+4)+(2 \lambda+5)=2 \\ 5 \lambda+12=2 \Rightarrow \lambda=-2 \end{array}$ Hence coordinates of point of inter section are $\equiv(-2+3,-4+4,-4+5)$ i.e. $(1,0,1)$ $\therefore$ Distance between $(3,4,5)$ and $(1,0,1)$ is $=\sqrt{(3-1)^{2}+(4-0)^{2}+(5-1)^{2}}=6$

Asked in: MHT CET 2020 (13 Oct Shift 1)

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