If (α, β, γ) is mirror image of the point (2, 3, 4) with respect to the line Then 2α + 3β + 4γ is
If (α, β, γ) is mirror image of the point (2, 3, 4) with respect to the line Then 2α + 3β + 4γ is

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
Similar Questions for you
....(1)
Let
Let
Put l1 and l2 in (1)
α = 3
Given , ,
Dot product with on both sides
... (1)
Dot product with on both sides
... (2)
(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)
For ‘B’, x = 2r + 1, y = 3r – 1, z = -2r + 1
As AB is perpendicular to the line,
direction ratios of AB
(2r + 1, 3r – 2, -2r – 1)
Equation of AB
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Maths NCERT Exemplar Solutions Class 11th Chapter Eight 2025
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