Q45 / 105 · NTA Abhyas (JEE Main) 2020 · Mathematics · Three Dimensional Geometry

Let P1: x+y+2z-4=0 and P2: 2x-y+3z+5=0 be two planes. Let A1,3,4 and B3,2,7 be two points in space. The equation of a third plane P3 through the line of intersection of P1 and P2 and parallel to AB is 

  • A
    x-4y-2z+3=0
  • B
    x-4y-2z+9=0
  • C
    2x-3y+4z+9=0
  • Correct answer
    D
    3y+z-13=0

Solution

Equation of P3 is P1+λP2=0
x1+2λ+y1-λ+z2+3λ-4+5λ=0
AB→=<2,-1,3>
a normal vector to plane P3 is <1+2λ,1-λ,2+3λ>
If AB is parallel to P3=0
⇒21+2λ-11-λ+32+3λ=0
⇒2+4λ-1+λ+6+9λ=0
⇒14λ+7=0
⇒λ=-12
Equation of required plane is 0+y×32+z12-132=0

i.e. 3y+z-13=0

Hence, the correct answer is option: 'D'.

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