6_условный_оператор

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Vir_4
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Input  first_edge");
            string ABAsString = Console.ReadLine();
            double AB = 0;
            if (!double.TryParse(ABAsString, out AB))
            {
                Console.WriteLine(" first_edge input is wrong");
                Console.ReadKey();
                return;
            }
            if (AB <= 0)
            {
                Console.WriteLine("first_edge is wrong");
                Console.ReadKey();
                return;
            }
            Console.WriteLine("Input second_edge");
            string BCAsString = Console.ReadLine();
            double BC = 0;
            if (!double.TryParse(BCAsString, out BC))
            {
                Console.WriteLine(" second_edge input is wrong");
                Console.ReadKey();
                return;
            }
            if (BC <= 0)
            {
                Console.WriteLine("second_edge is wrong");
                Console.ReadKey();
                return;
            }
            Console.WriteLine("Input third_edge");
            string CAAsString = Console.ReadLine();
             double CA = 0;
             if (!double.TryParse(CAAsString, out CA))
            {
                Console.WriteLine(" third_edge input is wrong");
                Console.ReadKey();
                return;
            }
            if (CA <= 0)
            {
                Console.WriteLine("third_edge is wrong");
                Console.ReadKey();
                return;
            }

            // Ввод окончен
            double Cos_1 = (CA*CA - AB*AB + BC*BC) / (2*CA*BC);
            double Cos_2 = (AB*AB - CA*CA + BC*BC) / (2*AB*BC);
            double Cos_3 = (AB*AB - BC*BC + CA*CA) / (2*AB*CA);
            if ((AB != BC) && (BC != CA) && ((Cos_1 < 0) || (Cos_2 < 0) || (Cos_3 < 0)))
            {
                double p = 0.5 * (AB + BC + CA);
                double for_sqrt = p * (p - AB) * (p - BC) * (p - CA);
                if (for_sqrt < 0)
                {
                    Console.WriteLine("Tringle are wrong");
                    Console.ReadKey();
                    return;
                }
                double s = Math.Sqrt(for_sqrt);
                Console.WriteLine("S = {0}", s);
                Console.ReadKey();
                return;
            }
            else
                Console.WriteLine("Tringle are not satisfies the task");
            Console.ReadKey();
        }
    }
}