1. The problem statement, all variables and given/known data 13 equal charges are placed in the corners of a regular 13-sided polygon. What is the force on a test chrage at the center? 2. Relevant equations principle of superposition symmetry 3. The attempt at a solution I am not sure if the net force is 0 or not. Had the polygon been 12-sided the symmetry would be obvious, but I'm not sure in this case. Can anyone explain if the net force is 0 or not?