Q31 / 60 · JEE Advanced 2015 (Paper 1) · Mathematics

In R3, consider the planes P1 :y=0 and P2 :x+z=1. Let P3, be a plane, different from P1 and P2, which passes through the intersection of P1 and P2. If the distance of the point 0, 1, 0, from P3, is 1, and the distance of a point (α, β, γ), from P3, is 2, then which of the following relations is (are) true ?

  • A
    2α+β+2γ+2=0
  • Correct answer
    B
    2α-β+2γ+4=0
  • C
    2α+β-2γ-10=0
  • Correct answer
    D
    2α-β+2γ-8=0

Solution

P1:y=0

P2:x+z=1

P3:y+λx+z-1=0


Figure
∴β+λα+γ-11+2λ2=±2

∴β+λα+γ-1=±21+2λ2

Figure
1-λ1+2λ2=±1
λ=-2   λ≠0

∴β-2α+γ-1=±23

2α-β+2γ+4=0 or 2α-β+2γ-8=0.

Hence, the correct answer is options: 'B', 'D'.

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