Q. 155.0( 2 Votes )
Find the coordinates of the foot of the perpendicular drawn from the point (1, 2, 3) to the line Also, find the length of the perpendicular from the given point to the line.
Given: Equation of line is
To find: coordinates of foot of the perpendicular from (1, 2, 3) to the line. And find the length of the perpendicular.
1. Equation of a line is
where is a point on the line and b1 : b2 : b3 is the direction ratios of the line.
2. Distance between two points (x1, y1, z1) and (x2, y2, z2) is
So the foot of the perpendicular is (3λ + 6, 2λ + 7, -2λ + 7)
Direction ratio of the line is 3 : 2 : -2
Direction ratio of the perpendicular is
⇒ (3λ + 6 - 1) : (2λ + 7 - 2) : (-2λ + 7 - 3)
⇒ (3λ + 5) : (2λ + 5) : (-2λ + 4)
Since this is perpendicular to the line,
3(3λ + 5) + 2(2λ + 5) – 2(-2λ + 4) = 0
⇒ 9λ + 15 + 4λ + 10 + 4λ – 8 = 0
⇒ 17λ = -17
⇒ λ = -1
So the foot of the perpendicular is (3, 5, 9)
= 7 units
Therefore, the foot of the perpendicular is (3, 5, 9) and length of perpendicular is 7 units.
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