Trig. equations needed

I know some basic trig. but how do i find an angle from an anchor point and a mving point? To help you off …

adjecent = _root.anchor._x-_root._xmouse;
opposite = _root.anchor._y-_root._ymouse;
hypotenuse = ((adjacent ^ 2)+(opposite ^ 2)) ^ 0.5;

If anyone knows thx in advance.