Codeforces C1. Simple Polygon Embedding

https://codeforc.es/contest/1354/problem/C1
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Derivation process ：

AC Code ：

#include <iostream>
#include <cstdio> 
#include <cmath>
using namespace std;
#define PI 3.141592653589// than 6 How many people are there 
int main(){
    
	int t;
	cin>>t;
	while(t--){
    
		double n,ans;
		scanf("%lf",&n);
		ans=1.0/tan(PI/(2.0*n));// Here is the radian value 
		printf("%.7lf\n",ans);
	}
	return 0;
}