Engineering
Mathematics
Equation of Straight Line in 3D
Distance from a Plane
Question

Find the co-ordinates of a point lying on the line x23=y+34=z17 which is at a distance 10 units from (2,–3,1).

(−32,−37,−71)

None of these

(32,37,71)

(−28,−43,−69)

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Solution
Given that the required point lies on the line x23=y+34=z17 .
The required point is at a distance of 10 units from (2,–3,1) 

By option verification,

(A) Substituting the point (32,37,71)  
    3223=37+34=7117
⇒ 10 = 10 = 10
Therefore, distance is (322)2+(37+3)2+(711)2=86.02 units
Hence, (32,37,71) is not the required point.
(B) Substituting the point (–28,–43,–69) 
    2823=43+34=6917
⇒  –10=–10 =–10
Therefore, distance is (282)2+(43+3)2+(691)2=86.02 units
Hence, (–28,–43,–69) is not the required point.
(C) Substituting the point (–32,–37,–71) 
    3223=37+34=7117
⇒  11.3 = 11.3 =10.28
Therefore, distance is (322)2+(37+3)2+(711)2=86.57 units
Hence, (–32,–37,–71) is not the required point.