#include <bits/stdc++.h>
#define ll long long
#define Ma 1000005
#define ld long double
using namespace std;
ld v,ri,d;
ld pi=acosl(-1);
ld eps=1e-6;

void sol()
{
    cin>>v>>ri>>d;
    ld len=8.0*sqrtl(2)*ri,ti=len/(2.0*v);
    ld go=ti*v+4*ri;
    ld ma=ti+(d-go)/(2*v);
    ld mi=ti/2+sqrtl((d-go/2)*(d-go/2)+4*ri*ri)/(2.0*v);
  //  printf("ma=%.8Lf mi=%.8Lf\n",ma,mi);
    if (d<=go)
    {
        ld ans=min(ti,d/v);
        printf("%.8Lf\n",ans);
        return;
    }
    //printf("gone\n");
    ld ans=d/v;
    ti/=2.0;
    //printf("ti=%.6Lf\n",ti);
    ld le=pi,re=pi*3.0/2.0;
    while (re-le>=eps)
    {
        ld mid=(le+re)/2.0;
        ld len=8*ri*(-cosl(mid/2.0));
        ld all=ti+len/(v*2.0);
        //printf("mid=%.6Lf all=%.6Lf\n",mid,all);
        ld dis=d-(2.0*ri+all*v);
        ld add=sqrtl(dis*dis+4*ri*ri-dis*4*ri*cosl(pi*3.0/2.0-mid));
        ld sita=acosl((dis*dis+add*add-4*ri*ri)/(2.0*dis*add));
        ld p=(mid-pi);
        ld delta=(4*v*v*cosl(p)*cosl(p)+12*v*v);
        ld px=(-2*v*cosl(p)+sqrtl(delta))/2.0;
        ld gama=acosl((5*v*v-px*px)/(4*v*v));
        ld ok=add/(2.0*v)+all;
        //printf("mid=%.10Lf ok=%.10Lf\n",mid,ok);
		if (sita-eps>=gama)
            le=mid;
        else{
        	//ld ok=add/(2.0*v)+all;
            //printf("mid=%.10Lf ok=%.10Lf\n",mid,ok);
            ans=min(ans,ok);
            re=mid;
        }
    }
    printf("%.8Lf\n",ans);
}


int main()
{
    ios::sync_with_stdio(0); cin.tie(0);
    ll tt;
    cin>>tt;
    while (tt--)
        sol();

    return 0;
}