Java给出3个点，做三角形判断

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问题：

给定平面上任意三个点的坐标(x1,y1)、(x2,y2)、(x3,y3)，检验它们能否构成三角形。

输入格式：

输入在一行中顺序给出6个[-100, 100]范围内的数字，即3个点的坐标x1, y1, x2, y2, x3, y3。

输出格式：

若这3个点不能构成三角形，则在一行中输出“Impossible”；若可以，则在一行中输出该三角形的周长和面积，格式为“L = 周长, A = 面积”，输出到小数点后2位。

输入样例1：

4 5 6 9 7 8

输出样例1：

L = 10.13, A = 3.00

输入样例2：

4 6 8 12 12 18

输出样例2：

Impossible

求解代码：

import java.text.DecimalFormat;import java.util.Scanner;//点class Point{//x坐标private double x;//y坐标private double y;public Point(double x, double y){this.x=x;this.y=y;}public double getX() {return x;}public void setX(double x) {this.x = x;}public double getY() {return y;}public void setY(double y) {this.y = y;}}//直线class Line{private Point point1;private Point point2;//斜率private double slope;private double length;public Line(Point point1 , Point point2){this.point1=point1;this.point2=point2;this.slope=(point1.getY()-point2.getY())/(point1.getX()-point2.getX());this.length=Math.sqrt( Math.pow(Math.abs(point1.getY()-point2.getY()), 2)+Math.pow(Math.abs(point1.getX()-point2.getX()), 2));}public double getSlope() {return slope;}public boolean  isParallel(Line line){if(this.slope==line.getSlope())return true;return false;}public double getLength() {return length;}}/*给定平面上任意三个点的坐标(x1,y1)、(x2,y2)、(x3,y3)，检验它们能否构成三角形。 *1. 不存在平行的两条直线 *2. 两边之和大于第三边 3. 两边直插小雨第三边 * */public class Main {public static void main(String[] args) {//控制台输入Scanner scanner = new Scanner(System.in);double x1,x2,x3,y1,y2,y3;//从控制台获得3个坐标点（x1,y1）,(x2,y2),(x3,y3)x1=scanner.nextDouble();y1=scanner.nextDouble();x2=scanner.nextDouble();y2=scanner.nextDouble();x3=scanner.nextDouble();y3=scanner.nextDouble();//构造成3个Point对象Point point1 = new Point(x1,y1);Point point2 = new Point(x2,y2);Point point3 = new Point(x3,y3);//得到3条直线Line line1 = new Line(point1,point2);Line line2 = new Line(point1,point3);Line line3 = new Line(point2,point3);//存储三条直线的长度double len1 = line1.getLength();double len2 = line2.getLength();double len3 = line3.getLength();//判断三条直线是存在平行if( line1.isParallel(line2) || line1.isParallel(line3) || line2.isParallel(line3)){System.out.println("Impossible");}//判断不平行的三条直线是否能构成三角形else if( (len1+len2)<len3 || (len1+len3)<len2 || (len2+len3)<len1 || Math.abs(len1-len2)>len3 || Math.abs(len1-len3)>len2 || Math.abs(len2-len3)>len1){System.out.println("Impossible");}else{//求周长double L = line1.getLength()+line2.getLength()+line3.getLength();double P = L/2.0;//求面积double S = Math.sqrt(P*(P-line1.getLength())*(P-line2.getLength())*(P-line3.getLength()));//结果保留两位小数DecimalFormat df = new DecimalFormat("#0.00");System.out.println("L = "+df.format(L)+", A = "+df.format(S));}}}

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