Need geometry code

I have the following tasks:
1. Given a vector and a point, I need to get an equation for a plane.
2. Given 3 intersecting planes, I need the point where they intersect (actually, that's the goal, not getting a plane).

I will probably be able to pull this off with 16-bit math, but there's a possibility that Double may be needed (unlikely). It'd be on a dsPIC, so C code is great, asm for the 16F or 18F would not be.

Not that I can't figure out how to implement this, but I kept looking through the geometry stuff and realized how long it's been since I did this sort of geometry and it'll "take awhile" to figure this out and it may be a better idea to just grab functions from elsewhere.

Have you checked Google? You should be able to find the vector/point equation easily enough. The three plane intersection might be a little more complicated though. My geometry is probably worse than yours =)