1. The problem statement, all variables and given/known data Two equal charges (Q = +0.80 nC) are situated at the diagonal corners A and B of a square of side x = 1.2 m as shown in the diagram. What is the magnitude of the electric field at point D? 2. Relevant equations E=kQ/r^2 3. The attempt at a solution First I converted 0.80 nC into C and got 8.0e-10 C. Using pythagorean's theorum I found 1.7 m as the distance between the two charges. I then used Coulomb's law as follows: 9e9*8e-10/1.7^2 which gave me 2.5. Since we want point D, I took the sin(45)2.5 + cos(45)2.5 and came up with 3.52 which was wrong. Any ideas where I goofed?