Chapter 4 Exercise 3, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

*4.3 (Geography: estimate areas) Find the GPS locations for Atlanta, Georgia; Orlando, Florida; Savannah, Georgia; and Charlotte, North Carolina from www.gps-data-team.com/map/ and compute the estimated area enclosed by these four cities. (Hint: Use the formula in Programming Exercise  4.2 to compute the distance between two cities. Divide the polygon into two triangles and use the formula in Programming Exercise  2.19 to compute the area of a triangle.)

public class ProgrammingEx4_3 {
 // Point(1) Atlanta, Georgia; 51.5138505182,-0.15690922737098845
 // Point(2) Orlando, Florida; 28.5383355,-81.37923649999999
 // Point(3) Savannah, Georgia; 32.0835407,-81.09983419999998
 // Point(4) Charlotte, North Carolina;35.2270869,-80.84312669999997
 public static void main(String[] args) {
 
  double x1 = 51.5138505182;
  double y1 = -0.15690922737098845;
 
  double x2 = 28.5383355;
  double y2 = -81.37923649999999;
 
  double x3 = 32.0835407;
  double y3 = -81.09983419999998;
 
  double x4 = 35.2270869;
  double y4 = -80.84312669999997;
 
  // Calculating 1st triangle; p1, p2 and, p3
  double side1 = Math.sqrt(Math.pow(x1 - x2, 2) + Math.pow(y1 - y2, 2));
  double side2 = Math.sqrt(Math.pow(x2 - x3, 2) + Math.pow(y2 - y3, 2));
  double side3 = Math.sqrt(Math.pow(x1 - x3, 2) + Math.pow(y1 - y3, 2));
  double s = (side1 + side2 + side3) / 2;
  double area = Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));
 
  // Calculating 2nd triangle; p1, p3 and, p4
 
  side1 = Math.sqrt(Math.pow(x1 - x3, 2) + Math.pow(y1 - y3, 2));
  side2 = Math.sqrt(Math.pow(x4 - x3, 2) + Math.pow(y4 - y3, 2));
  side3 = Math.sqrt(Math.pow(x1 - x4, 2) + Math.pow(y1 - y4, 2));
  s = (side1 + side2 + side3) / 2;
  area = Math.sqrt(s * (s - side1) * (s - side2) * (s - side3)) + area;
 
  System.out.print("The area enclosed by 4 cities is " + area + " km^2");
 
 }
 
}