In this work, the authors present a commonly used example in electrostatics that could be solved exactly in a conventional manner, yet expressed in a compact form, and simultaneously work out special cases using the method of images. Then, by plotting the potentials and electric fields obtained from these two methods, the authors demonstrate that these two methods provide identical solutions. Furthermore, a number of sum rules are deduced based on the arguments that these two methods should also give the same induced charge, and force. (Contains 9 figures.)