If the square of the shortest distance between the lines x-21= y-12= z+3-3 and x+12= y+34= z+5-5 is mn, where m, n are coprime numbers, then m+n is equal to :
- 14
- 6
- 21
- 9
Answer
(4) 9
Solution
b1 b2=2 i- j, | b1 b2|= 5, a2- a1=(-3,-4,-2)
d= |( a2- a1) ( b1 b2)|| b1 b2|= |-6+4| 5= 2 5
d2= 45 m+n=4+5=9
Answer: (4)