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Three Dimensional Geometry

Question
CBSEENMA12035715

Find the equation of the plane through the line of intersection of the planes x + y + z = 1 and 2x + 3y + 4z = 5 which is perpendicular to the plane x- y + z = 0. Also find the distance of the plane obtained above, from the origin.

Solution

Equation of the plane passing through the intersection of the planes x+y+z=1 and 2x+3y+4z=5 is:
left parenthesis straight x plus straight y plus straight z minus 1 right parenthesis plus straight lambda left parenthesis 2 straight x plus 3 straight y plus 4 straight z minus 5 right parenthesis space equals space 0
left parenthesis 1 plus 2 straight lambda right parenthesis straight x plus left parenthesis 1 plus 3 straight lambda right parenthesis straight y plus left parenthesis 1 plus 4 straight lambda right parenthesis straight z minus left parenthesis 1 plus 5 straight lambda right parenthesis equals 0
This space plane space space has space to space be space perpendicular space to space the space plane space straight x minus straight y plus straight z space equals space 0.
Thus comma
left parenthesis 1 plus 2 straight lambda right parenthesis 1 plus left parenthesis 1 plus 3 straight lambda right parenthesis left parenthesis negative 1 right parenthesis plus left parenthesis 1 plus 4 straight lambda right parenthesis 1 equals space 0
1 plus 2 straight lambda minus 1 minus 3 straight lambda plus 1 plus 4 straight lambda space equals space 0
1 plus 3 straight lambda space equals space 0
straight lambda equals negative 1 third
Thus, the equation of the plane is:
open parentheses 1 plus 2 open parentheses negative 1 third close parentheses close parentheses straight x plus open parentheses 1 plus 3 open parentheses negative 1 third close parentheses close parentheses straight y plus open parentheses 1 plus 4 open parentheses negative 1 third close parentheses close parentheses straight z minus open parentheses 1 plus 5 open parentheses negative 1 third close parentheses close parentheses equals space 0
open parentheses 1 minus 2 over 3 close parentheses straight x plus left parenthesis 1 minus 1 right parenthesis straight y plus open parentheses 1 minus 4 over 3 close parentheses straight z minus open parentheses 1 minus 5 over 3 close parentheses equals 0
straight x over 3 minus straight z over 3 plus 2 over 3 equals 0
straight x minus straight z equals negative 2
Thus comma space the space distance space of space this space plance space from space the space origin space is colon
open vertical bar fraction numerator negative left parenthesis negative 2 right parenthesis over denominator square root of 1 squared plus 0 squared plus 1 squared end root end fraction close vertical bar space equals space open vertical bar fraction numerator 2 over denominator square root of 2 end fraction close vertical bar equals space square root of 2

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