area shape ARC

hi guys

simple question, hard answer :P

I have made a php pie chart generator and it's awesome.
I want to add clickable area map to it.
But i'm dealing with arcs, not full circle. how can I achieve this?

thanks

I'd use a polygon shape and then put in the triangular points along with a number of points along the arc depending on the size of the area. It won't be perfectly round, but given enough points, it will work well enough.