I'm sorry if this has been asked, I've searched around and couldn't find it.
where a, b and c are vectors.
Q) Show that a*b = b*c = c*a
It could be the cross product. The last product is c times a, not the other way around.
Edit: And if it is the cross product, you may find it useful to write c = -a-b.
You then need to check that b*c and c*a are both equal to a*b (recall that the cross product is linear in both variables (like any good product), and that x*x=0 for all x).