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

typedef long long ll; typedef unsigned long long ull;
const int inf = 1e9; const ll llnf = 4e18;

template< class Tp > void chkmax( Tp &x , Tp y ) { x = max( x , y ); }
template< class Tp > void chkmin( Tp &x , Tp y ) { x = min( x , y ); }

double pi = acos( -1.0 );

void solve( ) {
	double v , r , d; cin >> v >> r >> d;

	auto simpson = [&] ( auto f , double l , double r ) -> double {
		auto calc = [&] ( double l , double r ) -> double { return ( f( l ) + f( r ) + 4 * f( ( l + r ) / 2 ) ) * ( r - l ) / 6; } ;
		auto F = [&] ( auto F , double l , double r , double eps = 1e-8 ) -> double {
			double S = calc( l , r ) , lS = calc( l , ( l + r ) / 2 ) , rS = calc( ( l + r ) / 2 , r );
			if( abs( lS + rS - S ) <= 15 * eps ) return lS + rS + ( lS + rS - S ) / 15;
			else return F( F , l , ( l + r ) / 2 , eps / 2 ) + F( F , ( l + r ) / 2 , r , eps / 2 );
		} ;
		return F( F , l , r );
	} ;

	auto check = [&] ( double t ) -> bool {
		double R = 2 * r; double X = d - v * t; if( X < 2 * R ) return false;

		auto f = [&] ( double theta ) -> double { return 1 / ( sqrt( sin( theta ) * sin( theta ) + 3 ) - sin( theta ) ); } ;
		double phi = pi - acos( R / ( X - R ) );
		double sum = ( R * simpson( f , 0 , phi ) + f( phi ) * sqrt( pow( X - R + R * cos( phi ) , 2 ) + pow( R * sin( phi ) , 2 ) ) ) / v;
		return sum <= t;
	} ;

	double lef = 0.0 , rig = ( d - 4 * r ) / v , ans = d / v;
	if( lef <= rig ) for( int T = 1; T <= 80; T ++ ) { double mid = ( lef + rig ) / 2; ( check( mid ) ) ? ( rig = mid , ans = mid ) : ( lef = mid ); }
	cout << fixed << setprecision( 15 ) << ans << "\n";
}

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