Let L1: x-12= y-23= z-34 and L2: x-23= y-44= z-55 be two lines. Then which of the following points lies on the line of the shortest distance between L1 and L2 ?
- ( 143,-3, 223 )
- (2,3, 13 )
- ( 83,-1, 13 )
- (- 53,-7,1 )
Answer
(1) ( 143,-3, 223 )
Solution
The shortest distance line is the common perpendicular: direction b1 b2=(-1,2,-1).
P=(2 +1, 3 +2, 4 +3), Q=(3 +2, 4 +4, 5 +5) with PQ (-1,2,-1)
= 13, =- 16, so P= ( 53,3, 133 )
Required line: through P with direction (1,-2,1)
Option (1): ( 143,-3, 223 )-P=(3,-6,3) (1,-2,1), so it lies on the line.
Answer: (1)