saslan

using System;
using System.IO;

namespace Figure
{
    abstract class Figure
    {
        public abstract double Area();

        public abstract double Perimeter();

        public abstract void ShowInfo();
    }

    class Rectangle : Figure
    {
        double a, b;

        public Rectangle(double a, double b)
        {
            this.a = a;
            this.b = b;
        }

        public override double Area()
        {
            return a * b;
        }

        public override double Perimeter()
        {
            return (a + b) * 2;
        }

        public override void ShowInfo()
        {
            Console.WriteLine("Прямоугольник со сторонами {0} и {1}", a, b);
        }
    }

    class Triangle : Figure
    {
        double a, b, c;

        public Triangle(double a, double b, double c)
        {
            this.a = a;
            this.c = c;
            this.b = b;
        }

        public override double Perimeter()
        {
            return a + b + c;
        }


        public override double Area()
        {
            double p = Perimeter() / 2;
            return Math.Sqrt(p * (p - a) * (p - b) * (p - c));
        }

        public override void ShowInfo()
        {
            Console.WriteLine("Треугольник со сторонами {0}, {1}, {2}", a, b, c);
        }
    }

    class Circle : Figure
    {
        const double pi = 3.14;

        double r;

        public Circle(double r)
        {
            this.r = r;
        }

        public override double Area()
        {
            return pi * r * r;
        }

        public override double Perimeter()
        {
            return 2 * pi * r;
        }

        public override void ShowInfo()
        {
            Console.WriteLine("Круг c радиусом {0}.", r);
        }
    }

    class Program
    {
        static void Main()
        {
            Figure[] arFigs = {
                new Rectangle(2,4),
                new Triangle(2,3,4),
                new Circle(5)
            };

            for (int i = 0; i < arFigs.Length; i++)
            {
                arFigs[i].ShowInfo();
                Console.Write("Периметр: {0}; Площадь: {1}\n\n", arFigs[i].Perimeter(), arFigs[i].Area());
            }
        }


    }


}