3. Three particles having charges of +q, +Q, and - Q are placed at the corners of an equilateral triangle of side a, as shown below. The net force on the particle with charge +q due to the other two charges is in the plane of the page and directed (A) vertically upward (B) vertically downward. (C) horizontally to the right (D) horizontally to the left (E) toward the charge - Q b. Find the magnitude of the force on the particle with charge +q due to the other two charges.