java语言程序设计(基础篇)第十版编程练习题[2.19]

package dome2_19;

import java.util.Scanner;

public class Dome2_19 {

public static void main(String[] args) {
Scanner input=new Scanner(System.in);
System.out.println("Enter three points for a triangle :");
double x1=input.nextDouble();
double y1=input.nextDouble();
double x2=input.nextDouble();
double y2=input.nextDouble();
double x3=input.nextDouble();
double y3=input.nextDouble();
double s1=Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
double s2=Math.sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
double s3=Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
double s=(s1+s2+s3)/2;
double area=Math.sqrt(s*(s-s1)*(s-s2)*(s-s3));
System.out.println("The area of the triangle is "+(int)(area*10)/10.0);

}

}