using System;

public class Program

{

    public static void Main()

    {

        //Soy Kelly 

        //entradas

        double r = 8, a = 4, e = 7, b = 5, c = 3, s = 9, t = 15, x = 2;

        //salidas

        double r1, r2, r3, r4, r5, r6;

        r1 = Math.PI * Math.Pow (r, 2);

        Console.WriteLine(r1);

        r2 = (Math.PI * Math.Pow(r,2) * a ) / 3;

        Console.WriteLine(r2);

        r3 = Math.Exp(t);

        Console.WriteLine(r3);

        r4 = (Math.Pow(a, 2) - Math.Pow(b, 2) - Math.Cos(x)) / 2;

        Console.WriteLine(r4);

        r5 = Math.Sqrt( (1 + Math.Cos(x)) / 2);

        Console.WriteLine(r5);

        r6 = Math.Sqrt(s*(s-a)*(s-b)*(s-c));

        Console.WriteLine(r6);

    }

}