The shortest distance between the lines x - 34 = y + 7-11 = z - 15 and x - 53 = y - 9-6 = z + 21 is:
- 185 563
- 187 563
- 178 563
- 179 563
Answer
(2) 187 563
Solution
Points A(3, -7, 1), B(5, 9, -2); directions b1 = (4, -11, 5), b2 = (3, -6, 1)
n = b1 b2 = vmatrix i & j & k\ 4 & -11 & 5\ 3 & -6 & 1 vmatrix = 19 i + 11 j + 9 k, | n| = 361 + 121 + 81 = 563
S.D. = projection of AB = 2 i + 16 j - 3 k on n:
d = | AB n || n| = 38 + 176 - 27 563 = 187 563
Answer: (2)