BBsecurity_cstdio

/// https://www.youtube.com/watch?v=l_ffdarcJiQ
#include <cstdio>
#include <cmath>
using namespace std;

int main()
{
    int n;
    scanf("%d",&n);
    int L,c,h;
    while(n--)
    {
        scanf("%d %d %d",&L,&c,&h);
        if(h==L)
        {
            printf("%d.00\n",c);
            continue;
        }
        double p=(double)(L-h);
        double q=(double)c*0.5,a,y,x;
        if(p==q)
        {
            printf("0.00\n");
            continue;
        }
        a=(double)((q+p)*(q-p))/(double)(2*p);
        y=q/a;
        x=2*a* asinh(y);
        if(x==(int)x)
            printf("%d.00\n",(int)x);
        else
            printf("%4.2f\n",x);
    }
    return 0;
}