How to get width and height of the bounding box of

Question

Possible Duplicate:
Calculate Bounding box coordinates from a rotated rectangle, Picture inside
AABB of rotated sprite?

I have a rectangle with a width of w and height of h. I rotate the rectangle r degrees(originating at its center point).

How can I determine the width(w2) and height(h2) of the bounding box after the rotation.