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Dot product between cross products

  • Thread starter quietrain
  • Start date
  • #1
654
2

Homework Statement


show (axb) . (cxd) =
|a.c b.c|
|a.d b.d|

The Attempt at a Solution



i have no idea. i don't know if the lines at the side are modulus lines or matrix brackets

but it seems that it has something to do with distribution law.

but i can't start proving if i don't even understand what the right hand side of the equation is ><

thanks for help!
 

Answers and Replies

  • #2
97
1
Right side is a determinant of this matrix. It's not so hard to prove, you could in example use Levi-Civita symbol to write your cross product, it goes in 3 steps afterwards.
 
  • #3
654
2
Right side is a determinant of this matrix. It's not so hard to prove, you could in example use Levi-Civita symbol to write your cross product, it goes in 3 steps afterwards.
oh i have done it. but i didn't use that symbol? thanks anyway!
 
  • #4
97
1
Well, you don't have to use it, that's just my favourite way to deal with cross product stuff :).
 

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