poj 1799 Yeehaa!

#include <iostream>#include <cstdlib>#include <cstring>#include <cstdio>#include <cmath>using namespace std;int main(){    int t;    scanf("%d", &t);    for (int i = 0; i < t; i++)    {        double r;        int n;        scanf("%lf%d", &r, &n);        printf("Scenario #%d:n%.3fnn", i + 1, (1 - 1 / (1 + sin(3.1415926 / n))) * r);    }    return 0;}