static void Main(string[] args)
{
Rectangle r = new Rectangle(10, 7);
double a = r.area();
Console.WriteLine("Area: {0}", a);
Console.ReadKey();
}
static void Main(string[] args)
{
Caller c = new Caller();
Rectangle r = new Rectangle(10, 7);
Triangle t = new Triangle(10, 5);
c.CallArea(r);
c.CallArea(t);
Console.ReadKey();
}