The square of the distance of the point (-2, -8, 6) from the line x-11= y-12= z-1 along the line x+51= y+5-1= z2 is equal to:
- 3
- 6
- 8
- 12
Answer
(2) 6
Solution
Distance 'along' a line is measured in the direction (1, -1, 2) of that line.
A point on the line through (-2, -8, 6) in this direction: (-2+t, -8-t, 6+2t)
It lies on x-11= y-12= z-1:
-3+t= -9-t2 3t=-3 t=-1
Check with the third ratio: 6+2t-1=-4=-3+t; meeting point (-3, -7, 4)
Distance2=(12+12+22)t2=6
Answer: (2)