#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;

int main(){


    double pi=acos(-1.0);
    double p=pi/180;

    int x,s,n;

    cin>>x;
    for(int i=1;i<=x;i++){

        cin>>n>>s;
        double t=180/n;
        double r = s/(2*sin(t*p));
        double area = pi*r*r - ((s*s*n)/(4*tan(t*p)));

        cout<<"Case "<<i<<": ";
        cout<<fixed<<setprecision(2)<<area<<endl;


    }

    return 0;
}