Walls and Ceilings - angled wall

I'm splitting a 20ft room to make two rooms. One wall will extend 8ft into the space from an exterior wall then make a 45 degree angle to connect to another existing wall. This short wall will be appx. 40 inches across and will have a prehung door installed. The floor and ceiling are pre-cast concrete, the interior walls are sheetrock. I will anchor the sole plate with adhesive and 3/8 sleeve anchors and the top plate with concrete screws. The new walls will be finished with sheetrock and painted.

At the outside corner where the 45 shows up, do I simply hang the rock and tape/mud that joint or do I have to build the studs into the corner? Said another way, does the end of the rock have to be supported to the very end or can I tape/mud the unsupported 2" that extend past the studs without fear of wall flex? Will corner bead work ok here?

Thanks in advance for any and all replies.

http://doityourself.com/wall/fwallstudwindow.htm

If you peck on the other interior corners in your home, you will find that there are studs all the way to the end of the drywall. The drywall is attached to and supported by the studs. It is very important that you frame sturdy corners for sturdy walls.