Question
Mathematics Question on Vector Algebra
The value of [(a−b)(b−c)(c−a)] is equal to
A
1
B
2
C
0
D
2[abc]
Answer
0
Explanation
Solution
∴[(a−b)(b−c)(c−a)]
=(a−b)⋅[(b−c)×(c−a)]
=(a−b)⋅[b×c−b×a−c×c+c×a]
=(a−b)⋅[b×c−b×a+c×a]
[∵c×c=0]
=a⋅[b×c]−a⋅[b×a]+a⋅[c×a]
−b⋅[b×c]+b⋅[b×a]−b⋅[c×a]
=[abc]−0+0+0−[bca]
=[abc]−[abc]
=0