杭电2080

//余玄定理+反三角函数
#include<stdio.h>
#include<math.h>
#define pi  3.14159265
int main()
{
    int n;
    double x1,x2,y1,y2,a,b,c,ans;
    while(~scanf("%d",&n))
    {
        while(n--)
        {
            scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);
            a=sqrt(x1*x1+y1*y1);
            b=sqrt(x2*x2+y2*y2);
            c=sqrt((y2-y1)*(y2-y1)+(x2-x1)*(x2-x1));
            ans=acos((a*a+b*b-c*c)/(2*a*b))*180/pi;
            printf("%.2lf
",ans);
        }
    }
}