public class Triangolo extends Poligono 
{
    public Triangolo(double x, double y, double z) 
    {
	super(new double[] {x, y, z});
    }
    public double getArea()
    {
	double a = getLato(0),
	       b = getLato(1),
	       c = getLato(2);
	double semi = (a+b+c)/2;
	return Math.sqrt((semi-a) * (semi-b) * (semi-c));
    }
}