/*

//Author:nunu

//

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <math.h>

int main(void)

{

    int n;

    double x[2], y[2], t;

    scanf("%d", &n);

    while (n-- && scanf("%lf%lf%lf%lf", x, y, x+1, y+1))

        printf("%.2f\n", (t=asin(fabs(x[0]*y[1]-x[1]*y[0])/sqrt(x[0]*x[0]+y[0]*y[0])/sqrt(x[1]*x[1]+y[1]*y[1]))/acos(-1)*180)?x[0]*x[1]<=0&&y[0]*y[1]<=0?180-t:t:x[0]*x[1]<0?180:0);

    return 0;

}

*/

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#define PI 3.141592653

int main()

{

    int n;

    double x1,x2,y1,y2,m,t;

    scanf("%d",&n);

    while(n--)

    {

              scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2);

              m=x1*x2+y1*y2;

              t=sqrt((x1*x1+y1*y1)*(x2*x2+y2*y2));

              printf("%.2lf\n",acos(m/t)/PI*);//这个是公式……不过也是网上来的

    }

    return ;

}