Thus the scalar product will be zero if any of the above three quantities are zero. Since the magnitudes of A and B are given to be non-zero, therefore,
if the cosine of the angle θ is zero, then the scalar product of the given vectors can be zero. Since cos90° = 0, therefore, if the angle between A and B is 90° then the scalar product of the given vectors is zero.
Pingback:Vectors and Equilibrium, Conceptual Questions … msa – msa