code: public void rotate(double cos, double sin, Point2D rotationCenter) {
  		Transformation2D temp = new Transformation2D();
  		temp.setRotate(cos, sin, rotationCenter);
  		multiply(temp);
  	}
docs: Rotates the transformation aroung a center point.
  
  @param cos
  The cos angle of the rotation.
  @param sin
  sin angle of the rotation.
  @param rotationCenter
  The center point of the rotation.