题意:求正五边形的内接正方形边长
给出正五边形边长
分析:y = sinY / sinX * x
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
using namespace std;
const double pi = acos(-1);
int main()
{
double temp = sin(pi*108/180)/sin(pi*63/180);
double x,y;
while(~scanf("%lf",&x))
{
y = temp * x;
printf("%.10lf\n",y);
}
return 0;
}