15. (a) Use a counterexample to show that (A x B) x C is not necesarilly equal to A x (B x C)
(b) Prove that A x (B x C) = (A.C)B ? (A. B)C. Can von give a geometric interpretation of this equation?
A vector proof involving cross-produts and dot.products is provided. The solution is detailed and well presented. The response received a rating of "5/5" from the student who originally posted the question.