The Problem is finding the E-field at a point P that is h distance from the center of a rectangle (along a line normal to its surface) with Length L and width W with a constant charge density sigma. This is for an intro E&M class that is supposed to use up through calculus 2, and we have not yet discussed Gausses Law. So supposedly this should be able to be solved without any double or triple integration. Since I have had vector calculus I should be able to understand any help using vector calculus techniques. Here is what I have tried so far and where I have gotten stuck. Attached is an image of the problem. Just in case the image doesn't work, I have set it up so that: Theta is the angle on the surface between a point along the width at the center and point P. Phi is the angle on the surface between a point along the length at the center and point P. I started by saying: dE=kdqsin(theta)sin(phi)/r^2 But dq=sigmadA and r=sqrt(W^2+L^2+h^2) and sin (theta)=h/sqrt(W^2+h^2) and sin(phi)=h/sqrt(L^2+h^2) Thus dE=ksigmah^2dwdl/[(L^2+W^2+h^2)sqrt[(h^2+L^2)(W^2+h^2)]] From this point I have tried lots of algebraic stuff to make it easier to integrate, but I just have not been able to integrate this at all, and I am not sure if it is possible to do so. I am worried that my set up may be wrong. Any help would be much appreciated. Thank you.