08/09/16 17:26:34
>>725
#include<stdio.h>
#include<math.h>
double a(int n)
{
double an;
if (n == 0) {
return 1.0;// 6角形の1辺の長さ
}
an = a(n - 1);
return (an / (sqrt(2 + sqrt(4 - (an * an)))));
}
int main(void)
{
int n = 10;
double pai;
pai = a(n) * pow(2, n) * 6 / 2;
printf("%f\n", pai);
return 0;
}