poj 1799 Yeehaa!

#include <iostream>
#include <math.h>
const double pi=3.1415926535898;
using namespace std;
int main()
{
    int t,i;double R,n;
    cin>>t;
    for(i=1;i<=t;i++)
    {
        cin>>R>>n;
        printf("Scenario #%d:\n",i);
        printf("%.3lf\n\n",R*sin(pi/n)/(1+sin(pi/n)));
    }
    return 0;
}