This battery has a difference in potential energy between the positive terminal and negative terminal which units express this difference in energy

The magnitudes of each of the two displacement vectors r1 and r2 are equal to 29.0 m. determine the smallest angle between the two vectors in order for the magnitude of the sum of the two vectors (r1 + r2) to be 27 times greater than the magnitude of the difference of the two vectors (r1 − r2).