static void Main(string[] args)
 {
     TwoDShape[] shapes = new TwoDShape[4];
     shapes[0] = new Triangle("right", 8.0, 12.0);
     shapes[1] = new Rectangle(10);
     shapes[2] = new Rectangle(10, 4);
     shapes[3] = new Triangle(7.0);
     for (int i = 0; i < shapes.Length; i++)
     {
         Console.WriteLine("object is " + shapes[i].name);
         Console.WriteLine("Area is " + shapes[i].Area());
         Console.WriteLine();
     }
 }
 // Construct a copy of a TwoDShape object.
 public TwoDShape(TwoDShape ob)
 {
     Width  = ob.Width;
     Height = ob.Height;
     name   = ob.name;
 }