using System; using System.Globalization; class TriangleArea { static void Main() { Console.WriteLine("enter perimeter: "); double p = double.Parse(Console.ReadLine(), CultureInfo.InvariantCulture); double a = p / 3.0; double s = Math.Sqrt((1.5 * a) * (0.5 * a) * (0.5 * a) * (0.5 * a)); Console.WriteLine("side\tarea"); Console.WriteLine("{0}\t{1}", a.ToString("F2", CultureInfo.InvariantCulture), s.ToString("F2", CultureInfo.InvariantCulture)); } }