uva 10286 Trouble with a Pentagon

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;}