Three particles P1, P2, and P3 are located at the points (-2.00, -1.00), (0, 2.00), and (3.00, -1.00), respectively. P1 has a charge of 5.00 µC, but the charges of P2 and P3 are unknown. However, the three particles exert no net force on a charged particle that is placed at the origin. You are asked to find the unknown charges. (a) Use the fact that the net horizontal force on the particle at the origin is zero to find the unknown charge on P3. (b) Then use the fact that the net vertical force on the particle at the origin is zero to find the unknown charge on P2.