1. The problem statement, all variables and given/known data Let F1,F2 and F3 be the forces experiences by a test charge q at a point in a region of electric and magnetic fields E and B, respectively, for velocities v1,v2 and v3, respectively, of the charge. If F1,F2 and F3 are such that A= F1xF2 + F2xF3 + F3xF1 =/= 0, that is, their tips do not lie on a straight line when drawn from a commom point. -> Show that B=(1/q)|(F2-F1)/[(v2-v1)xA]|A *(The character that Bolded means vector, eg. F1) 2. Relevant equations I think it is related to the Lorentz Force Equation. 3. The attempt at a solution My teacher told us to find the relationship between B and A, which we can assume B=kA and to find k. I don't really have any idea how to work on it as i don't know how to get the direction of each force. Please Help me..I am really despair as i have worked on it for a really long time ..