public abstract class Shape
public Shape(int numSides)
this.numSides = numSides;
public abstract string GetPerimeter();
public abstract double GetArea();
public class IsoscelesTriangle : Shape
public override double GetArea()
double area = (side * height) / 2;
public override GetArea():
public class Rectangle : Shape
public Rectangle(double width, double height)
public double getPerimeter()
return 2 * (width + height);
public static void Main()
Console.WriteLine("Hello World");