1. The problem statement, all variables and given/known data I've taken the liberty to translate the problem, along with its corresponding diagram, into an image: http://img15.imageshack.us/img15/9695/questionm.jpg [Broken] angle q1 = 53* angle q2 = 37* angle q3 = 90* 2. Relevant equations F21 = kq1q2/(r21)^2 F31 = kq1q3/(r31)^2 Sine Law 3. The attempt at a solution I think I have a good idea on how to solve this problem. First, here is my vector FBD: http://img36.imageshack.us/img36/5599/vectorw.jpg [Broken] I'm not sure if I did it properly. The other issue is I'm not sure whether the angle x is 37 or 53 degrees. My personal take on it is that it is 53 degrees, because vector F21 is drawn at 37 degrees; because that 37 degrees isn't in the triangle, I believe the only way to get an angle is to consider the angle 53 (complimentary angle). But because of this, I am second-guessing whether my FBD is right in the first place or if I am wrong to infer the angle that way. Secondly, I have calculated: F21 = 2.7x10^-23 N F32 = 8.8x10^-23 N So, my approach to this problem is to apply the sine law (as soon as I can determine angle x) to get all the angles within the triangle and then to get a magnitude for the net force vector. So: 1. Is my vector FBD correct? 2. Is my inference of angle x correct? 3. Is my approach to the problem sound? I'll appreciate any help I can get.