Cutting a circle

Hi all,

I need to make shapes like this based on a value for graph purposes - usually I would just create a cutting shape based on trig (this shape representing around 60%) and subtract it from the path - I have about 30 graphs to do and I need to base it on a variable, and I want to use script - I'm sure there must be a better way, and I'm hoping you guys have the answer.

Thanks in advance

Dave