Help, Help, Help, I have a wedding cake to do this weekend, and they changed the design, it's a very simple design, but they want me to put traiangle fondant pieces all around the cake. and I want to know how to measure the pieces so they go around the cake evenly. I will be icing it in buttercream, and then attaching the fondant pieces. Any help will be appreciated, thanks in advance.

I would use a skinny piece of ribbon or some string to measure around the cake, after it is iced. Then you can figure out how big they will need to be.
I wouldn't worry too much about them meeting exactly in the back if it is going to be against a wall or some place where people won't be going behind it, but you can at least get it pretty close.
Personally, I would be more worried about them all being exactly the same size. Hope you are using a template or cutter.