Remark
I am deliberately putting an answer in so that you can choose a brainly for the other responder. My answer will not be on topic, so you can choose the other person quite easily.
I found it interesting that all regular polygons with sides of 4 and above that are even will be a possible solution to your pizza problem. The circle enclosing the regular polygon will have diameters running through the center if the opposite vertices are connect. I've uploaded three of them. I cannot prove this is so, but it is an interesting fact.
The left one is a decagon
The middle one is an 18 agon (I don't know the proper term)
The right one is a 14 a gon (again I don't know the proper term)
Conclusion
1. Probably all even vertici regular polygons have this feature in common.
2. Next time you order a pizza, think about the regular polygon that created the cuts.
