Engineering
Mathematics
Plane and Its Different Forms
Question

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?

2α + β + 2γ + 2 = 0

2α – β + 2γ – 8 = 0

2α + β – 2γ – 10 = 0

2α – β + 2γ + 4 = 0

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Solution

Equation of plane P3 will be (x + z – 1) + λy = 0

⇒ x + λy + z – 1 = 0

Distance from (0, 1, 0) is equal to 1

|0+λ·1+01|1+λ2+1= 1

⇒ (λ – 1)2 = λ2 + 2 ⇒ λ2 – 2λ + 1 = λ2 + 2

2λ=  1 λ= 12.

  Plane will be x – y2 + z – 1 = 0 ⇒ 2x – y + 2z – 2 = 0

Distance from (α, β, γ) = 2

⇒ |2αβ+2γ2|22+12+22 = 2 ⇒ 2α – β + 2γ – 2 = ± 6

⇒ 2α – β + 2γ = 8          or         2α – β + 2γ = – 4.