Let the plane containing the line of intersection of the planes P1 : and P2 : pass through the points and . Then the distance of the point from the plane P2 is
- A.
- B.
- C.
- D.
Show answer and solution
Correct option: C
Solution
The family of planes through the line of intersection is P1 + μP2 = 0:
(1+2μ)x + (λ+4+μ)y + (1+μ)z = 1+2μ
Substituting (0,1,0): (λ+4+μ) = 1+2μ → λ+3 = μ
Substituting (1,0,1): (1+2μ) + (1+μ) = 1+2μ → 2+3μ = 1+2μ → μ = -1
So λ+3 = -1 → λ = -4.
The point is (2λ, λ, -λ) = (-8, -4, 4).
Distance from P2: 2x+y+z=2 is |2(-8)+(-4)+4-2|/√(4+1+1) = |-16-4+4-2|/√6 = |-18|/√6 = 18/√6 = 3√6.
(1+2μ)x + (λ+4+μ)y + (1+μ)z = 1+2μ
Substituting (0,1,0): (λ+4+μ) = 1+2μ → λ+3 = μ
Substituting (1,0,1): (1+2μ) + (1+μ) = 1+2μ → 2+3μ = 1+2μ → μ = -1
So λ+3 = -1 → λ = -4.
The point is (2λ, λ, -λ) = (-8, -4, 4).
Distance from P2: 2x+y+z=2 is |2(-8)+(-4)+4-2|/√(4+1+1) = |-16-4+4-2|/√6 = |-18|/√6 = 18/√6 = 3√6.
[JEE Main 2023 · 24 Jan · Shift 2]