#include <iostream>
#include <cmath>
using namespace std;
int main()
{
double X1,X2,X3,Y1,Y2,Y3,s1,s2,s3;
cout<<"請輸入三角形的第壹個角的坐標(X,Y):"<<endl;
cin>>X1>>Y1;
cout<<"請輸入三角形的第二個角的坐標(X,Y):"<<endl;
cin>>X2>>Y2;
cout<<"請輸入三角形的第三個角的坐標(X,Y):"<<endl;
cin>>X3>>Y3;
s1=sqrt((X1-X2)*(X1-X2)+(Y1-Y2)*(Y1-Y2));
s2=sqrt((X1-X3)*(X1-X3)+(Y1-Y3)*(Y1-Y3));
s3=sqrt((X3-X2)*(X3-X2)+(Y3-Y2)*(Y3-Y2));
if(((s1+s2>s3)&&(s1-s2<s3))||((s1+s3>s2)&&(s1-s3<s2))||((s3+s2>s1)&&(s3-s2<s1)))
if((s1*s1+s2*s2==s3*s3)||(s2*s2+s3*s3==s1*s1)||(s1*s1+s3*s3==s2*s2))
cout<<"這是壹個直角三角形!"<<endl;
else
if(s1==s2||s1==s3||s2==s3)
cout<<"這是壹個等腰三角形!"<<endl;
else
if(s1==s2&&s2==s3&&s1==s3)
cout<<"這是壹個等邊三角形!"<<endl;
else
cout<<"這三點可以構成壹個壹般的三角形!"<<endl;
else
cout<<"這三點構不成壹個三角形!"<<endl;
return 0;
}