static void Main(string[] args)
{
Krug k = new Krug(5);
Treugolnik t = new Treugolnik(4, 4, 5);
Console.WriteLine(SAll.S(k));
Console.WriteLine(SAll.S(t));
Console.WriteLine(Treugolnik.TruePrTreugolnik(t));
}
public static double S(Krug r)
{
return(Math.PI * r.R * r.R);
}