Let P be the foot of the perpendicular from the point (1,2,2) on the line L: x-11= y+1-1= z-22. Let the line r= (- i+ j-2 k )+ ( i- j+ k ), , intersect the line L at Q. Then 2(PQ)2 is equal to :
- 25
- 27
- 19
- 29
Answer
(2) 27
Solution
Point on L: ( +1, - -1, 2 +2); AP=( , - -3, 2 ) (1,-1,2)
⇒ + +3+4 =0 ⇒ =- 12 ⇒ P ( 12,- 12,1 )
[figure]
(-1,1,-2) on the second line satisfies L (all ratios =-2) ⇒ Q(-1,1,-2)
PQ= ( 32,- 32,3 ) ⇒ PQ2= 272
∴ 2PQ2=27
Answer: (2)