Two charges, + q and - q, occupy two corners of an equilateral triangle, as shown in

Question:

Two charges, + q and - q, occupy two corners of an equilateral triangle, as shown in FIGURE 19-51.
(a) If q = 1.8 µC and r = 0.50 m, find the magnitude and direction of the electric field at point A, the other vertex of the triangle. Let the direction angle be measured counterclockwise from the positive x axis.
(b) What is the total electric flux through the surface indicated in the figure?
(c) Explain why Gauss's law cannot easily be used to find the magnitude of the electric field at point A.
Figure 19-51.