#include<iostream>
#include<stdio.h>
#include<cmath>
using namespace std;
int main()
{
	int n,i,test;
	double R;
    cin>>test;
	for(i=1;i<=test;i++)
	{
	   cin>>R>>n;
	   if(i<test)
			printf("Scenario #%d:\n%.3f\n\n",i,R*sin(acos(-1)/n)/(1+sin(acos(-1)/n)));
		else
			printf("Scenario #%d:\n%.3f\n",i,R*sin(acos(-1)/n)/(1+sin(acos(-1)/n)));
	}
	return 0;
}
你看看　知道自己哪错了吧