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Let the foot of the perpendicular from the point \mathrm{1,2,4} on the line \mathrm{\frac{x+2}{4}=\frac{y-1}{2}=\frac{z+1}{3}} be  \mathrm{P}. Then the distance of \mathrm{P} from the plane \mathrm{3 x+4 y+12 z+23=0}  is

Option: 1

5


Option: 2

\frac{50}{13}


Option: 3

4


Option: 4

\frac{63}{13}


Answers (1)

best_answer

Let the foot of perpendicular be

\mathrm{P(4 \lambda-2,2 \lambda+1,3 \lambda-1)} \\

\mathrm{A:(1,2,4) \quad A P \perp L} \\

\mathrm{\Rightarrow(4 \lambda-2-1,2 \lambda+1-2,3 \lambda-1-4)-(4,2,3)=0 }\\

\mathrm{\Rightarrow 4(4 \lambda-3)+2(2 \lambda-1)+3(3 \lambda-5)=0} \\

\mathrm{\Rightarrow 29 \lambda=29 \Rightarrow \lambda=1} \\

\mathrm{\Rightarrow P(2,3,2) }

Distance of \mathrm{P } from  \mathrm{3 x+4 y+12 z+23=0 } is

\mathrm{ d =\frac{3 \times 2+4 \times 3+2 \times 12+23}{\sqrt{3^{2}+4^{2}+12^{2}}} }\\

\mathrm{=\frac{65}{13}=5}

Hence the correct answer is option 1

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