Let a plane P pass through the point (3, 7, -7) and contain the line, (x-2)/(-3) = (y-3)/2 = (z+2)/1. If distance of the plane P from the origin is d, then d² is equal to ________.
Let a plane P pass through the point (3, 7, -7) and contain the line, (x-2)/(-3) = (y-3)/2 = (z+2)/1. If distance of the plane P from the origin is d, then d² is equal to ________.
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1 Answer
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Vector on plane: (3-2, 7-3, -7- (-2) = (1,4, -5).
Line direction vector (-3,2,1).
Normal to plane n = (1,4, -5)× (-3,2,1) = (14,14,14) or (1,1,1).
Plane: 1 (x-3)+1 (y-7)+1 (z+7)=0 ⇒ x+y+z-3=0.
d = |-3|/√3 = √3. d²=3.
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....(1)
Let
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α = 3
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(a – 1) × 2 + (b – 2) × 5 + (g – 3) × 1 = 0
2a + 5b + g – 15 = 0
Also, P lie on line
a + 1 = 2λ
b – 2 = 5λ
g – 4 = λ
2 (2λ – 1) + 5 (5λ + 2) + λ + 4 – 15 = 0
4λ + 25λ + λ – 2 + 10 + 4 – 15 = 0
30λ – 3 = 0
a + b + g = (2λ – 1) + (5λ + 2) + (λ + 4)

Take
x = 2λ + 1, y = 3λ + 2, z = 4λ + 3
= (α − 2)
Now,
(α − 2) ⋅ 2 + (β − 3) ⋅3 + (γ − 4) ⋅ 4 = 0
2α − 4 + 3β − 9 + 4γ −16 = 0
⇒ 2α + 3β + 4γ = 29
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