#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
#define PI 3.1415927
int main(){
    int t,n;
    double R,tmp;
    scanf("%d",&t);
    for(int i=1;i<=t;i++){
        scanf("%lf%d",&R,&n);
        printf("Scenario #%d:\n",i);
        tmp = cos((n-2)*1.0*PI/2/n); 
        printf("%.3lf\n\n",tmp*R/(1+tmp));
    }
    return 0;
}