public class Circle implements TwoDShape  {
    private double radius;

    public Circle (double radius) {
        this.radius = radius;
    }

    public double area() {
        return Math.PI*radius*radius;
    }

    public double circumference() {
        return Math.PI*2.0*radius;
    }

    public void describe() {
        System.out.print("Circle[radius=");
        System.out.print(radius);
        System.out.println("]");
    }

}