thanks for your advice, but it does not help me with the problem because I have to assume that I do not know the definition of F = v X B for the prove. Therefore, I want to proof that the force vector is NOT parallel to the plane without considering the definition of the croos product
here is the problem:
prove that the vector of the magnetic force cannot be parallel to the plane that contains the vector of the particle's velocity and magnetic field.
someone please help me to solve this, thanks so much for your time.