1. The problem statement, all variables and given/known data Derive and simplify an expression for the electrical potential energy of the charge configuration. It's an equilateral triangle with charges +q, -q and +q. 2. Relevant equations Ep=Kq2/r 3. The attempt at a solution I know how to do this with squares (it's basically exploding the symmetry). For example in a square there are charges #s1,2,3 and 4. I do the equation with 1 respect to 2,3 and 4. Then with 2 respect to 3 and 4. Finally, 3 respect to 4. I see which terms cancel out, then it's all algebra. I did this in this triangle, getting -kq2/r as the final expression, which for some reason doesn't convince me (perhaps because it's too simple? lol). I don't know if in the square you are ''unconsciently'' multiplying by the sin90, therefore I should multiply by sin60 here. If so, is it just multiplying sin60 by each term? I do know that electrical potential energy is a vector quantity and not a scalar quantity like voltage, right? Thanks.