posted by Diana .
three spheres, each with a negative charge of 4.0*10^-6 C, are fixed at the vertices of an equilateral triangle whose sides are 0.20m long. Calculate the magnitude and direction of the net force on each sphere.
So far i have drawn a diagram and used the formula Fe= kq1q2/r^2 and got the answer 3.6 which is correct so far... but i don't know what to do after that to get the net force on each of the spheres.
any ideas please?