//Criando Classe
using System;

namespace Course
{
    class Triangulo
    {
        private double A { get; set; }
        private double B { get; set; }
        private double C { get; set; }
        public Triangulo() { }
        public Triangulo(double A, double B, double C)
        {
            this.A = A;
            this.B = B;
            this.C = C;
        }
        public double Area()
        {
            double p = (this.A + this.B + this.C) / 2.0;
            return Math.Sqrt(p * (p - this.A) * (p - this.B) * (p - this.C));
        }
    }
}

//_________________________________________________________

using System;
using System.Globalization;

namespace Course
{
    class Program
    {
        static void Main(string[] args)
        {
            double xA,xB,xC,yA,yB,yC;
            Console.WriteLine("Entre com as medidas do triângulo X:");
            xA = double.Parse(Console.ReadLine(), CultureInfo.InvariantCulture);
            xB = double.Parse(Console.ReadLine(), CultureInfo.InvariantCulture);
            xC = double.Parse(Console.ReadLine(), CultureInfo.InvariantCulture);

            Console.WriteLine("Entre com as medidas do triângulo Y:");
            yA = double.Parse(Console.ReadLine(), CultureInfo.InvariantCulture);
            yB = double.Parse(Console.ReadLine(), CultureInfo.InvariantCulture);
            yC = double.Parse(Console.ReadLine(), CultureInfo.InvariantCulture);

            var areaX = new Triangulo(xA,xB,xC).Area();
            var areaY = new Triangulo(yA,yB,yC).Area();

            Console.WriteLine("Área de X = " + areaX.ToString("F4", CultureInfo.InvariantCulture));
            Console.WriteLine("Área de Y = " + areaY.ToString("F4", CultureInfo.InvariantCulture));

            if (areaX > areaY)
            {
                Console.WriteLine("Maior área: X");
            }
            else
            {
                Console.WriteLine("Maior área: Y");
            }
        }
    }
}