Q32 / 90 · JEE Main 2023 (10 Apr Shift 2) · Mathematics

Let the image of the point P(1, 2, 6) in the plane passing through the points A(1, 2, 0) and B(1, 4, 1) C(0, 5, 1) be Q(α,β,γ) . Then α2+β2+γ2 equal to

  • Correct answer
    A
    65
  • B
    62
  • C
    76
  • D
    70

Solution

Plane passes through the points

A(1, 2, 0), B(1, 4, 1) and C(0, 5, 1)

We know that the equation of a plane passing through three non-collinear points x1,y1,z1,x2,y2,z2,x3,y3,z3 is x-x1y-y1z-z1x2-x1y2-y1z2-z1x3-x1y3-y1z3-z1=0

⇒x-1y-2z-01-14-21-00-15-21-0=0

⇒x-1y-2z-0021-131=x-12-3-y-20+1+z0+2=0

⇒-x+1-y+2+2z=0

⇒   x + y – 2z = 3     ....…(i) 

Now image of P(1, 2, 6) in (i)

x-11=y-21=z-6-2=-2(-9-3)6=4

x = 5, y = 6, z = -2

⇒α=5,β=6,γ=-2

∴  α2+β2+γ2=65

Hence this is the required option.

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

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