You are supposed to calculate the area of a polygon based on number of inputs given bythe user. Polygon can be a square, a rectangle or a triangle.

 /* Area of a polygon based on number of inputs given by the user */

import java.io.*;

import java.util.*;

class Polygon

{

   void area(double a)

   {

System.out.println("Area of Square = " + a*a);

   }

   void area(double l,double b)

   {

System.out.println("Area of Rectangle = " + l*b);

   }

   void area(double a,double b,double c)

   {

double s = (a+b+c)/2;

double d = s*(s-a)*(s-b)*(s-c);

System.out.println("Area of Triangle = " + String.format("%.2f",Math.sqrt(d)));

   }

}

class PolygonArea_4B

{

    public static void main(String args[])

    {

Polygon p = new Polygon();

Scanner s = new Scanner(System.in);

System.out.print("Enter side of a square : ");

double a = s.nextDouble();

p.area(a);

System.out.print("Enter sides of a rectangle : ");

double l = s.nextDouble();

double b = s.nextDouble();

p.area(l,b);

System.out.print("Enter three sides of a triangle : ");

double x = s.nextDouble();

double y = s.nextDouble();

double z = s.nextDouble();

p.area(x,y,z);

    }

}