#### Will

I assume that I have to use a spherical gaussian surface with 1/4 of its area corresponding to the size of the disk. Thats where I am confused. Do I make the top of the sphere just touch the bottom of the disk and have radius b, or do I construct it over the top of the disk, like a dome? And how do I acount for the fact that the electric feild lines wont be perpendicular to the surface of the disk because it is not round? Will this problem involve calculus, or is more of a geometry type problem?