ABSTRACT
This chapter considers another set of plates that intersect the first set at right angles, thereby producing a cylindrical region with a rectangular cross section. But there is a more symmetrical procedure here; begin with the three-dimensional delta function construction. We employ two coordinate systems in the transverse plane perpendicular to the axis of the triangular cylinder. One is the conventional rectangular frame— coordinates x and y—with its origin placed at the center of the inscribed circle. The second is a trilinear coordinate system based on the three unit vectors directed from the center of the inscribed circle to the three apexes. The potential that is Green's function can be extrapolated in a way similar to that of the parallel plates, by reflection in the three sides of the equilateral triangle.
