Let d be the distance of the point of intersection of the lines x + 63 = y2 = z + 11 and x - 74 = y - 93 = z - 42 from the point (7, 8, 9). Then d2 + 6 is equal to :
- 75
- 78
- 72
- 69
Answer
(1) 75
Solution
General points: (3k - 6, 2k, k - 1) and (4t + 7, 3t + 9, 2t + 4)
Equating x and y: 3k - 4t = 13, 2k - 3t = 9 k = 3, t = -1
z-check: k - 1 = 2 = 2t + 4 ✓ ⇒ point of intersection (3, 6, 2)
d2 = (7 - 3)2 + (8 - 6)2 + (9 - 2)2 = 16 + 4 + 49 = 69
d2 + 6 = 75
Answer: (1)