using System;

​

​

abstract class Shape  // base class (parent) 

{

  protected int numSides;// Vehicle field

  public int NumSides { // declare property

  get { return numSides; } // read-only property

  }

​

  public abstract void getArea();

  public abstract void getPerimeter();

​

}

​

​

​

 class Rectangle : Shape  // derived class (child)

{

 public int width;

 public int height;

 public double area;

 public double perimeter;

 public Rectangle(int width, int height){

 this.width=width;

 this.height=height;

 }

 public override void getPerimeter(){

     this.perimeter=2*(this.width+this.height);

     Console.WriteLine("perimeter of this rectangle is: {0}", this.perimeter);

 }

 public override void getArea(){

     this.area=(this.width*this.height);

     Console.WriteLine("area is of this rectangle: {0}", this.area);

 }

}

​

​

​

 class IsoscelesTriangle : Shape   // derived class (child)

{

 public int bases;

 public int height;

 public double area;

 public double perimeter;

 public IsoscelesTriangle(int bases, int height){

 this.bases=bases;

 this.height=height;

 }

 public override void getArea(){

     this.area=(this.bases*this.height)/2;

     Console.WriteLine("area is of this IsoscelesTriangle: {0}", this.area);

 }

 public override void getPerimeter(){

     double b=this.bases/2;

     double c=(this.height)*(this.height)+b*b;

     double d=Math.Sqrt(c);

     this.perimeter=2*d+this.bases;

     Console.WriteLine("perimeter of this triangle is: {0}",this.perimeter);

 }

}

​

​

​

​

​

public class Program

{

    public static void Main()

    {  

        Rectangle rec = new Rectangle(5,6);

        rec.getPerimeter();

        rec.getArea();

        IsoscelesTriangle tri= new IsoscelesTriangle(3,4);

        tri.getArea();

        tri.getPerimeter();

    }

}