The foot of perpendicular of the point 2 , 0 , 5 on the line x + 1 2 = y - 1 5 = z + 1 - 1 is α , &#946…

The foot of perpendicular of the point 2,0,5 on the line x+12=y-15=z+1-1 is α,β,γ. Then. Which of the following is NOT correct?
  1. αβγ=415
  2. αβ=-8
  3. βγ=-5
  4. γα=58

Solution

Given line is

L:x+12=y-15=z+1-1=λ (let)

 

Let foot of perpendicular is P2λ-1,5λ+1,-λ-1

PA=3-2λi^-5λ+1j^+6+λk^

Direction ratio of line is

b=2i^+5j^-k^

Now, PAL, so

PA·b=0

23-2λ-55λ+1-6+λ=0

6-4λ-25λ-5-6-λ=0

-30λ-5=0

λ=-16

So,

P2λ-1,5λ+1,-λ-1Pα,β,γ

Now,

α=2-16-1=-43 α=-43

β=5-16+1=16β=16

γ=-λ-1=16-1 γ=-56

So,

βγ=-15-5

 

Asked in: JEE Main 2023 (25 Jan Shift 2)

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