public class RegularPolygon implements Base {

    protected final int number;
    protected double length;
    
    public RegularPolygon ( int number, double length ) {
        if ( number < 3 ) {
            throw new IllegalArgumentException("Zu wenig Kanten");
        }
        
        this.number = number;
        this.length = length;
    }

    public double getPerimeter() {
        return number * length;
    }

    public double getArea() {
        /* Aus der Formelsammlung */
        return (number * length * length) / (4 * Math.tan(Math.PI / number));
    }
}