1. The problem statement, all variables and given/known data Point charges Q, -2Q and 3Q are situated at the corners A, B and C respectively of an eqilateral triangle of side l, and another point charge q, of the same sign as Q, is placed at the centre of this triangle. What is the force acting on the charge q, and what is the angle between the direction of this force and the side AB of the triangle? 2. Relevant equations 3. The attempt at a solution I know that when you have a point charge experiencing forces as a result of several other point charges (electric fields), you resolve the vector forces geometrically and the resultant gives you the direction &magnitude of the resultant force, but what happens when the charge under investigation doesn't lie in line with the other charges? When i resolve the forces using x and y axes at 000degrees and 090degrees, centre being at the location of charge q i get the wrong answer. I'm stuck from there.