Let a line L be perpendicular to both the lines L1 : x+13= y+35= z+57 and L2 : x-21= y-44= z-67. If is the acute angle between the lines L and L3 : x- 872= y- 471= z2, then is equal to :
- 32 2
- 52 2
- 53 2
- 43 2
Answer
(2) 52 2
Solution
L is perpendicular to L1 and L2 direction of L (3, 5, 7) (1, 4, 7)
vmatrix i & j & k\ 3 & 5 & 7\ 1 & 4 & 7 vmatrix=7 i-14 j+7 k (1, -2, 1)
Direction of L3 : (2, 1, 2)
= |1 2+(-2) 1+1 2| 6 3= 23 6
= 1- 454= 5054= 5 23 6
= = 5 22= 52 2
Answer: (2)