#include<iostream>
#include<algorithm>
#include<string.h>
#include<vector>
#include<cmath>
using namespace std;
// #define debug(x) cout<<"[debug]"#x<<"="<<x<<endl
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const ld eps=1e-10;
const int INF=0x3f3f3f3f,mod=998244353;
const ll INFF=0x3f3f3f3f3f3f3f3f;

#ifndef ONLINE_JUDGE
#define debug(...)
#include<debug>
#else
#define debug(...)
#endif

const ld PI=acos(-1);
int sign(ld x)
{
    if(abs(x)<eps) return 0;
    else if(x<0) return -1;
    else return 1;
}
int dcmp(ld x,ld y)
{
    if(abs(x-y)<eps) return 0;
    else if(x<y) return -1;
    else return 1;
}
ld v,r,d;

ld V(ld x)
{
    ld cx=cos(x);
    ld t=(-cx+sqrtl(cx*cx+3))*v;
    return t;
}
ld f(ld x)//自行修改f函数
{
    return 2*r/V(x);
}
ld simpson(ld a,ld b)
{
    ld mid=(a+b)/2;
    return (b-a)*(f(a)+4*f(mid)+f(b))/6;
}
ld merge_block(ld l,ld r,ld s)
{
    // debug(l,r);
    ld mid=(l+r)/2;
    ld left=simpson(l,mid);
    ld right=simpson(mid,r);

    if(abs(s-(left+right))<eps) return left+right;
    else return merge_block(l,mid,left)+merge_block(mid,r,right);
}
bool check(ld t)
{
    ld d2=d-v*t;

    ld a=2*r;
    ld c=d2-2*r;

    ld detal=asin(a/c);
    ld res=merge_block(0,PI/2,simpson(0,PI/2))+merge_block(0,detal,simpson(0,detal))+sqrtl(c*c-a*a)/V(detal);
    return res<=t;
}
void solve()
{
    scanf("%Lf%Lf%Lf",&v,&r,&d);
    ld res=d/v;
    if(sign(d-4*r)>=0)
    {
        ld lo=0,hi=(d-4*r)/v-eps;
        while(hi-lo>eps)
        {
            ld mid=(lo+hi)/2;
            if(check(mid)) hi=mid;
            else lo=mid;
        }
        if(check(lo+eps))
        res=min(res,lo);
    }
    printf("%.15Lf\n",res);
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        solve();
    }
}