4 charge particles are at the corners of a square of side "a" find q
2q O------------O q
3q O------------O4q
E= Ke( q1/r^2)*vector(r)1 + Ke (q2/r^2)* vector r2 + Ke (q3/r^2)*vector r3
E=Ke(2q/a^2)i + ke(3q/2a^2)(icos45.0 + jsin45.0) + ke(4q/a^2)j
I gess the question is how they got from...