rotating an ellipse about an axis
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if i make an ellipse bounded by a rectangle. how can i rotate it ? as in if i have rx,ry,cx,cy,topleft x,toplefy, bottomrightx,bottomrighty

iused the formula

angle=taninverse(ry/rx) 
and i keep adding the angle that is angle=angle + taninverse(ry/rx)

the angle is too small to see the difference.
please  provide another formula to calctulate teh angle with the given parmeteres


to have a look at the ellipse with the bounded rectangle frame
http://svg-edit.googlecode.com/svn/branches/2.5.1/editor/svg-editor.html