The shortest distance between the lines r= ( 13 i+2 j+ 83 k )+ (2 i-5 j+6 k ) and r= (- 23 i- 13 k )+ ( j- k ), , R, is :
- 5
- 3
- 2 3
- 15
Answer
(2) 3
Solution
a1= 13 i+2 j+ 83 k, b1=2 i-5 j+6 k; a2=- 23 i- 13 k, b2= j- k
b1 b2= vmatrix i & j & k\ 2 & -5 & 6\ 0 & 1 & -1 vmatrix=(5-6) i-(-2-0) j+(2-0) k=- i+2 j+2 k
| b1 b2 |= 1+4+4=3
a2- a1=- i-2 j-3 k
( a2- a1 ) ( b1 b2 )=1-4-6=-9
d= |-9|3=3
Answer: (2)