#include <bits/stdc++.h> 
using namespace std;
using ll =long long;
#define all(v) v.begin(),v.end()
 #define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)

void solve() {
double T,u,L;cin>>T>>u>>L;
T*=100;
u*=100;
L*=100;
double ans=-1*u*T+sqrt(u*u*T*T+2000*u*L);
if(ans<=0.0) {
  cout<<"0.00"<<endl;
  return ;
}

string s;
ans*=0.36;
s=to_string(ans);
string t="";
for(auto x:s) {
  if(x=='.') break;
  t+=x;
}
ll a=stoll(t);
cout<<fixed<<setprecision(2);
cout<<(double)a/100.0<<endl;



}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
    ll t;cin>>t;
    for(ll i=0;i<t;i++) {
        solve();
    }
}