URI ONLINE JUDGE SOLUTION 1292

Problem Number: 1292
Problem Name: Trouble with a Pentagon
Author’s Name: By Shahriar Manzoor Bangladesh
Timelimit: 2
Problem Category: AD-HOC
Problem Source: https://www.urionlinejudge.com.br/judge/en/problems/view/1292

Solution: 

#include <stdio.h>
#include <math.h>

const double pi = atan(1.0)*4;

int main(){
    double f, senos;
   
    senos = sin((108*pi)/180) / sin((63*pi)/180);
   
    while(scanf("%lf",&f) != EOF){
                         printf("%.10lfn",senos*f);
    }
    return 0;
}