#include <bits/stdc++.h>
using namespace std;

typedef long double db;
const db eps=1e-10;
const db pi=acos(-1);
int sign(db k){
	if (k<-eps) return -1;
	else if (k>eps) return 1;
	return 0;	
}
int cmp(db k1,db k2){return sign(k1-k2);}

db f(db theta){
	db s=sin(theta);
	return (sqrtl(s*s+3)+s)/3;
}

double simpson(double l, double r) {
    return (f(l) + 4 * f((l + r) / 2) + f(r)) * (r - l) / 6;
}
double Integral(double l, double r, double eps, double st) {
    double mid = (l + r) / 2;
    double sl = simpson(l, mid);
    double sr = simpson(mid, r);
    if (std::abs(sl + sr - st) <= 15 * eps)
        return sl + sr + (sl + sr - st) / 15;
    return Integral(l, mid, eps / 2, sl) + Integral(mid, r, eps / 2, sr);
}
double Integral(double l, double r) {
    return Integral(l, r, eps, simpson(l, r));
}

db solve(db v,db r,db d){
	db ans=d/v;
	r=r*2;
	db L=0,R=(d-2*r)/v-eps;
	if (R<L) return ans;
	auto check=[&](db t){
		db x=d-v*t-r;
		db theta=acos(r/x);
		db t1=Integral(0,pi-theta)*r/v;
		db t2=hypot(x-r*cos(theta),r*sin(theta))*f(theta)/v;
		return t1+t2<=t;
	};
	for (int cc=1;cc<=100;cc++){
		db mid=(L+R)/2;
		if (check(mid)) R=mid;
		else L=mid;
	}
	if (check(R)) ans=min(ans,R);
	return ans;
}

int main(){
	ios_base::sync_with_stdio(false);
	int T;
	cin >> T;
	for (;T--;){
		db v,r,d;
		cin >> v >> r >> d;
		cout << fixed << setprecision(12) << solve(v,r,d) << "\n";
	}
	return 0;	
}