Area of Geometric Shapes in C++

In this C++ program the area of geometric shapes (circle, rectangle, and triangle) is calculated easily through classes by asking the user a choice that which shape he wants to deal with, the code is:

    //area of geometric shapes in C++
    #include<iostream>
    #include<windows.h>
    using namespace std;
    #define pi 3.141592654
    #define full 2.0
     
    int square(int x)
    {
    return x*x;
    }
     
    // class declration
    class Area{
     
        int X,Y;    //taking two argumnet data members
        public:
        Area(int x,int y):X(x),Y(y){} //constructor with two argumnets 
        //data functions
        float circle(int x,int y)    //for area of the circle
        {
            cout<<"ntttArea of the Circle is :";
            return pi*square(x);
        }
     
        float rectangle(int l,int w) //for area of the rectangle
        {
            cout<<"ntttArea of the Rectangle is :";
            return l*w;
        }
     
        float triangle(int b,int h)    //for area of the triangle
        {
            cout<<"ntttArea of the Triangle is :";
            return (b*h)/full;
        }
    }; //class end
     
    void fun() // function for clear screen and Sleep
    {
        Sleep(2000);cout<<"nntttReturning to Menu";
        for (int i=0;i<=5;i++)
        {
            cout<<" .";
            Sleep(400);
        }
        system("cls");
    } // fun end
     
    // main body
    int main(void)
    {
        int first,second,choice;
        cout<<"nEnter the first argument :";cin>>first;
        cout<<"nEnter the second argument :";cin>>second;
        system("cls");
        Area instance(first,second);// set the value by pass to the constructor of the object called instance
     
        while (1) {    // loop for infinite running expect when 4 is pressed which is terminating case 
     
                    cout << "nttt --------------MENU ------------ " << endl
                    << "ttt      Press 1. Area of Circle " << endl
                    << "ttt      Press 2. Area of Rectangle" << endl
                    << "ttt      Press 3. Area of Triangle" << endl
                    << "ttt      Press 4. To Exit " << endl
                    << "nttt ------------------------------- " << endl
                    << "tttYour Choice :";
            cin>>choice;
            switch(choice){//switch        
                case 1:
                cout<<instance.circle(first,second);fun();//passing by value the function for area of circle by the object        
                break;
                case 2:
                cout<<instance.rectangle(first,second);fun();// same for the other functions
                break;
                case 3:
                cout<<instance.triangle(first,second);fun();    
                break;
                case 4:
                exit(1);    // termninating case to escpae from while and terminate
                break;
                default:
                cout<<"Wrong Input ";// for other wrong inputs
            }
        }
        return 0;
    }

The functions with relative comments are mentioned in the above code, the user is first asked to enter the arguments and then a menu appears offering the area of shape the user needs to select.