[Splitting a donut.....]

Thanks everyone, I'll have a go!

[Splitting a donut.....]

Brand new to graphic design, so apologies if this is really obvious (also tried searching but can't quite find what I'm after). 

If I have a donut shape (or two circles, subtracted from each other) and I want to separate them out into, say, 20 segments. How would you go about that?

I've tried creating pies and intersecting and I've tried creating a 20 pronged star and intersecting but when I do so, everything just disappears. 

Any pointers welcome!

 

Thanks