Get bounding box of rotated rectangle.

Newbie & Debugging Questions
#1

So, I have a rectangle with a known x, y, width and height.

http://s28.postimg.org/98vuq1cdl/rectangle.png

The top left corner is the x:y coordinate where x is increasing while moving right and y while moving down.

I then rotate it with a known value(the rectangle is rotated around its center point):

http://s28.postimg.org/qng2yb9ih/rotated_rectangle.png

I want to calculate the position of the red dot as well as the new width and height.