算法提高 12-1三角形   外心坐标

 1 #include<bits/stdc++.h>
 2 using namespace std;
 3 int main()
 4 {
 5 double x1,y1,x2,y2,x3,y3;
 6 double a,b,c,p;
 7 double  aa,bb,zz,aa1,bb1,zz1;
 8     scanf("%lf %lf",&x1,&y1);
 9     scanf("%lf %lf",&x2,&y2);
10     scanf("%lf %lf",&x3,&y3);
11     a=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
12     b=sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
13     c=sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
14     printf("%.2lf\n",a+b+c);//周长
15     p=(a+b+c)/2.0;
16     printf("%.2lf\n",sqrt(p*(p-a)*(p-b)*(p-c)));//面积
17     aa=2*(x1-x2);
18     bb=2*(y1-y2);
19     zz=x1*x1-x2*x2+y1*y1-y2*y2;
20     aa1=2*(x3-x2);
21     bb1=2*(y3-y2);
22     zz1=x3*x3-x2*x2+y3*y3-y2*y2;
23     printf("%.2lf %.2lf\n",((zz*bb1)-(zz1*bb))/((aa*bb1)-(aa1*bb)),
24            ((aa*zz1)-(aa1*zz))/((aa*bb1)-(aa1*bb)));//外心
25     printf("%.2lf %.2lf\n",(x1+x2+x3)/3.0,(y1+y2+y3)/3.0);//重心
26     return 0;
27 }