/*hdu6097[二分+解析几何] 2017多校6*/

#include <bits/stdc++.h>

using namespace std;

const double eps=1e-;

struct node{

    double x,y;

    node(double X=0.0,double Y=0.0):

    x(X),y(Y){}

}p,q;

double dist(node a,node b){

    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));

}

int T;

double A,B,C,a,b,c,h,R;

bool check(){

    a=sqrt(b*b+c*c);

    A=c*c;

    B=-2.0*a*a*h;

    C=a*a*h*h-a*a*b*b+b*b*R*R;

    double delta=B*B-4.0*A*C;

    //cout<<"delta: "<<delta<<endl;

    if(delta>=0.0){//判断复根

        double yy1=0.5*(-B+sqrt(delta))/A;

        double yy2=0.5*(-B-sqrt(delta))/A;

        if(R*R-yy1*yy1>=0.0||R*R-yy2*yy2>=0.0)

            return true;

        else return false;

    }

    else return false;

}

void solve(){

    double t1,t2;

    t1=(p.x+q.x)*0.5;

    t2=(p.y+q.y)*0.5;

    h=dist(node(t1,t2),node());

    c=0.5*dist(p,q);

    double l=,r=R-h;

    for(int i=;i<;i++){

        b=(l+r)*0.5;

        if(check()){

            r=b;

        }

        else{

            l=b;

        }

    }

    b=(l+r)*0.5;

    printf("%.8f\n",2.0*sqrt(b*b+c*c));

    /*....*/

}

int main(){

    //freopen("1002.in","r",stdin);

    //freopen("out.out","w",stdout);

    scanf("%d",&T);

    while(T--){

        scanf("%lf",&R);

        scanf("%lf%lf",&p.x,&p.y);

        scanf("%lf%lf",&q.x,&q.y);

        solve();

    }

    return ;

}