#include <iostream>

#include <stdio.h>

#include <math.h>

using namespace std;

int main()

{

int t;

double a,b,c,angle,z;

double x,y,v,g = 9.8,T,ans1,ans2;

scanf("%d",&t);

while(t--)

{

scanf("%lf%lf%lf",&x,&y,&v);

if(x==0&&y==0)

printf("0\n");

else if(x==0&&y>0)

printf("90\n");

else

{

a = g*pow(x,2)/(2*pow(v,2));

b = -x;

c = y+a;

T = pow(b,2) - 4*a*c;

angle = 0;

if(T<0)

printf("-1\n");

else

{

ans1 = ((-b)+pow(T,1.0/2))/(2*a);

ans2 = ((-b)-pow(T,1.0/2))/(2*a);

if(ans1>=0) angle = atan(ans1);

if(ans2>=0)

{

z =  atan(ans2);

if(z<angle) angle = z;

printf("%.6f\n",angle);

}

if(ans1<0&&ans2<0)

printf("-1\n");

}

}

}

return 0;

}