Hey lytwynk.
Hint: Use the fact that the cross product is associative and re-group [a x (a x b)] = (a x a) x b.
Hello, we were given a few practice problems in class the other day and one of them asks...
Simplify a x [a x (a x b)] dot c (where the x refers to cross product)
I have tried to simplify it but have ended up with about a page and a half of computation that I don't know what to do with.
I imagine there is a trick to this but I am clueless. If anyone can help I would appreciate it.
Sorry you are right: it is not associative.
Try using the Jacobi identity and you should get some cancellations:
Jacobi identity - Wikipedia, the free encyclopedia