4. The diagram shows a rectangular array of four point charges and the forces three of the point charges exert on the fourth point charge (q,). The fourth point charge is in static equilibrium under the influence of the three forces acting on it. If 0 = 60 and F, = 10 N, find the value of F,. Note that the free-body diagram for the point charge q, is superimposed on the figure. Box your answer. Hint: Use the rectangular coordinate system included on the diagram to resolve F2 into its horizontal and vertical components. -92 + 93 F 2 --X + 91 + 9 4