public class Cercle extends Forme {
    private double r;
    public Cercle(double cx, double cy, double r) {
        super(cx, cy);
        this.r = r;
    }
    @Override
    public void agrandissement(double r) {
        this.r *= r;
    }
    @Override
    public String toString() {
        return "Cercle de centre " +
                "(" + cx + ", " + cy + ")"
                + " et de rayon " + r;
    }

}