1. The problem statement, all variables and given/known data System with 3 charged particles red, yellow, and blue. The blue and red have a positive charge, while the yellow has a negative charge. The blue particle lies at (0,0). The red charge lies at (d1,0). The Yellow charge lies at (d2cos(θ), -d2sin(θ)). The Fon blue is (0,-F); F>0. q of yellow is 2q. What is the charge on the red particle in terms of q, d1, d2, and theta. 2. Relevant equations Coulomb's law. F=(K*q1*q2)/d^2 3. The attempt at a solution http://i249.photobucket.com/albums/gg221/cidr1337/394254_297418573698401_1519950841_n.jpg edited for kushan's question.