//prepare for coding{{{
#include<bits/stdc++.h>

#define RELEASE
#ifndef RELEASE
#define FL
#define DB(...) fprintf(stderr,__VA_ARGS__)
#endif 

typedef double DB;

const DB EPS=1e-8;

using namespace std;

const DB PAI=acos(-1);

inline int Read(){
	char c=getchar();
	int res=0;
	bool b=0;
	while(c>'9'||c<'0')
		b=(c=='-'),c=getchar();
	while(c>='0'&&c<='9')
		res=(res<<3)+(res<<1)+c-'0',c=getchar();
	return b?-res:res;
}

DB v,r,d;
//}}}

//solve{{{
const int B=5000;

inline DB Ftheta(DB theta){
	DB sn=sin(theta);
	return 2/(sqrt(sn*sn*4+12)-sn*2)/v;
}

inline DB Simpson(DB lim){
	DB d=lim/B,res=Ftheta(0)+Ftheta(lim);
	for(int i=1;i<B;i+=2)
		res+=4*Ftheta(i*d);
	for(int i=2;i<B;i+=2)
		res+=2*Ftheta(i*d);
	return res*d/3;
}
//}}}

//main{{{
inline void Solve(){
	scanf("%lf%lf%lf",&v,&r,&d);
	DB ll=PAI/2,rr=PAI,ans=PAI;
	while(rr-ll>EPS){
		DB mid=(ll+rr)/2,t=Simpson(mid)*r*2,alpha=atan2(sin(mid)*2*r,d-2*r-v*t+cos(mid)*2*r);
		DB x=-cos(mid)*2*r+2*EPS*cos(alpha)-EPS,y=sin(mid)*2*r-2*EPS*sin(alpha);
		if(x*x+y*y>4*r*r)
			ans=rr=mid;
		else
			ans=ll=mid;
	}
	//printf("%lf\n",ans);
	if(ans+EPS>PAI)
		return printf("%.10lf\n",d/v),void();
	DB anst=Simpson(ans)*r*2;
	DB x=cos(ans)*2*r+d-r*2-anst*v,y=sin(ans)*2*r;
	//printf("%lf %lf %lf %lf\n",anst,x,y,d/v);
	printf("%.10lf\n",min(anst+sqrt(x*x+y*y)/v/2,d/v));
}

int main(){
#ifdef FL
	freopen(".in","r",stdin);
	freopen(".out","w",stdout);
#endif
	int T=Read()+1;
	while(--T)
		Solve();
	return 0;
}
//}}}
//《象》曰：泽灭木，大过。君子以独立不惧，遁世无