A point charge of -.70microC is fixed to one corner of a square. An identical charge is fixed to the diagonally opposite corner. A point charge q is fixed to each of the remaining corners. The net force acting on either of the charges q is zero. Find the magnitude and algebraic sign of q. The only equation I know for this type of proble is F=[k(q1)(q2)]/r^2 Please help me sbraman I have tried to work this out by setting up the above equation so that the r^2 would cancel since I don't have that. I also have tried to figure it out using a right triangle but all of my answers are incorrect.