#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
struct node
{
double x,y;
node(){}
node(double a,double b)
{
x=a;
y=b;
}
};
double radius;//radius圆半径
node tcircle(node pt1, node pt2, node pt3)
{
double x1 = pt1.x, x2 = pt2.x, x3 = pt3.x;
double y1 = pt1.y, y2 = pt2.y, y3 = pt3.y;
double a = x1 - x2;
double b = y1 - y2;
double c = x1 - x3;
double d = y1 - y3;
double e = ((x1 * x1 - x2 * x2) + (y1 * y1 - y2 * y2)) / 2.0;
double f = ((x1 * x1 - x3 * x3) + (y1 * y1 - y3 * y3)) / 2.0;
double det = b * c - a * d;
if( fabs(det) < 1e-5)
{
radius = -1;//三点共线返回半径-1,圆心0 0
return node(0,0);
}
double x0 = -(d * e - b * f) / det;
double y0 = -(a * f - c * e) / det;
radius = hypot(x1 - x0, y1 - y0);
return node(x0, y0);
}
int main()
{
node a,b,c;
while(scanf("%lf%lf%lf%lf%lf%lf",&a.x,&a.y,&b.x,&b.y,&c.x,&c.y)!=EOF)
{
node point=tcircle(a,b,c);
printf("圆心:%.2f %.2f 半径:%.2f\n",point.x,point.y,radius);
}
return 0;
}
三个点确定一个圆
最新推荐文章于 2024-06-05 14:36:41 发布