using System; //Лист 3

public class Triangle

{ public double Area1(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 Area2(int a, int b, double angle)

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

 public double Area3(int a, int h)

 {return a*h/2.0;}

  public double Area4(int a, int b, int c, int R)

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

 public double Area5(int a, int b, int c, double r)

 {double p=(a+b+c)/2; return p*r;}

}