Three charges are fixed at the corners of a square of side length d = 2.5 cm. One charge has q = 3.2 nC and the other two have charge -q. d - 9 O (a): 5 points Find the magnitude of the electric field at point P, which is at the fourth corner of the square. Give your answers either to two significant figures in V/m, or symbolically in terms of (any and/or all of) q, d, and co