trouble in the fold

Hello all,
My name is Ken, and I am using Autodesk Inventor Pro 2014. I am having problems trying to draw a part in "sheet metal". My problem is in curves. I cant seem to figure out how to draw the part and the be able to "flatten" it, so that I can get the proper dimensions needed. Can this be done? Attached is an example of what I am trying to do. ( note the curve ) the 2 straight sides I can figure out it's just that darn curve.
Thanks, Ken
http://forums.augi.com/attachment.ph...id=99051&stc=1