using System;

public class Program

{

    class Triangle

    { public double Area(int a, int b, int c)

      { double p = (a + b + c) / 2.0;

        return Math.Sqrt(p * (p - a) * (p - b) * (p - c));

      }

      public double Area(int a, int b, double angle)

      { return a * b * Math.Sin(angle) / 2; }

      public double Area(int a, int h)

      { return a * h / 2.0; }

      public double Area(int a, int b, int c, int R)

      { return a * b * c / (double) (4 * R); }

      public double Area(int a, int b, int c, double r)

      { double p = (a + b + c) / 2;

        return p * r;

      }

   }

}