Math question

hi there,
i am really stuck.
I have a movieClip c and in this a movieClip called mc.
mc has the regristration point in the middle.
I would like to move c so that mc is in the center of the stage, but the problem is that mc is also rotated, so i need to calculate how much x and y I have to add because of the rotation.
this is what i have so far. My stage is 600x300.

const MID_STAGE_Y:Number = 200;
const MID_STAGE_X:Number = 300;

c.rotation =*-1;

To understand the problem I set up a test fla. please take a short look. Probably this is pretty easy for someone understanding the math behind it. I would love to understand it myself but did not get it till now. Thanks in advance for any reply on this !