#include <bits/stdc++.h>
using namespace std;
using ull=unsigned long long;
using ll=long long;
const double eps=1e-8;
double v,d,r;
double f(double x){
    return sqrt(3+sin(x)*sin(x))+sin(x);
}
double simpson(double l,double r){
    return (r-l)*(f(l)+f(r)+4*f((l+r)/2))/6;
}
double asr(double l,double r,double ans){
    double m=(l+r)/2,a=simpson(l,m),b=simpson(m,r);
    if(fabs(a+b-ans)<eps)   return ans;
    return asr(l,m,a)+asr(m,r,b);
}
double check(double alfa){
	return	2.0*r/3*asr(0,alfa,simpson(0,alfa))-2.0*r/3*tan(alfa)*f(alfa)-(d+2*r/cos(alfa));
}
const double Pi=acos(-1);
void solve() {
	cin>>v>>r>>d;
	d-=2*r;
	double l=Pi/2,ri=Pi;
	while(fabs(l-ri)>eps){
		double mid=(l+ri)/2;
		//cout<<check(mid)<<'\n';
		if(check(mid)>=0)	l=mid;
		else ri=mid;
	}
	if(fabs(check(l))>eps)	printf("%.6f\n",(d+2*r)/v);
	else{
		printf("%.6f\n",(d+2*r/cos(l))/v);
	}
}

int main() {
	ios::sync_with_stdio(0),cin.tie(0);
	int _ = 1; 
	cin >> _;
	while(_--) solve();
	return 0;
}