Originally Posted by

**Olbert** Hi - this is my first post on this forum so please be nice.

I have been thinking about a problem my university physics lecturer proposed and explained in class:

Where would an object be pulled by gravity if it was on the inside of a hollow sphere with the same size and mass as the earth?

This was years ago and I forgot the answer, but I set about to answer it mathematically using the various laws of physics I remember.

Anyways, long story I am stuck with a fairly ugly integral. A quick search of the standard integrals on wiki heralded no solution.

I need to solve an integral in the form of:

Integrate: (cos^2(theta)/(A^2-sin^2(theta)) d(theta)

I have no idea how to write that properly but if I was to say it to someone I would say :Integral of cos squared on 'a' squared minus sine squared.

Thanks