杭电acm1071

http://acm.hdu.edu.cn/showproblem.php?pid=1071

一条抛物线跟一条直线围成一个图形，给出两个交点和曲线最高点的坐标，求出面积，自己退出各个公式的系数，然后定积分求出结果

#include<stdio.h>
int main()
{
 int t;
 double x1,x2,x3,y1,y2,y3,a,b,c,k,h,s;
 scanf("%d",&t);
 while(t--)
   {
    scanf("%lf%lf",&x1,&y1);
    scanf("%lf%lf",&x2,&y2);
    scanf("%lf%lf",&x3,&y3);
        k=(y3-y2)/(x3-x2);
        h=y2-k*x2;//直线斜截式的斜率和截距
        a=(((y2-y1)/(x2-x1))-((y3-y2)/(x3-x2)))/(x1-x3);
        b=((y2-y1)/(x2-x1))-(a*(x1+x2));
        c=y3-(a*x3*x3+b*x3);//抛物线的a，b，c
        s=((a/3)*x3*x3*x3+((b-k)/2)*x3*x3+(c-h)*x3)-((a/3)*x2*x2*x2+((b-k)/2)*x2*x2+(c-h)*x2);//定积分求面积
    printf("%.2lf\n",s);
   }
   return 0;
}