题目：

思路：纯高等数学问题，不过不是很好积分，具体积分思路及过程参考大佬博客——

AC代码：

1 #include 
     
       2 #include 
      
        3 #include 
       
         4 #include 
        
          5 #include 
         
           6  7 using namespace std; 8  9 #define pi acos(-1.0)10 11 double h;12 13 double cal(double a) {14     return pi * cos(a) - a * cos(a) + sin(a) - pow(sin(a), 3) / 3;15 }16 17 double calV(double b) {18     double a = acos(2 * tan(b) - 1.0);19     return (cal(a) - cal(pi)) / tan(b);20 }21 22 int main()23 {24     int T;25     scanf("%d", &T);26     while(T--) {27         scanf("%lf", &h);28         double v = pi * h;29         if(h < 1e-10)30             printf("0.00000\n");31         else if(h >= 1.0) {32             double a = atan(2.0 - h);33             printf("%.5f\n", pi / cos(a));34         }35         else {36             double l = 0, r = pi / 4;37             while(r - l > 1e-9) {38                 double m = (l + r) / 2;39                 if(calV(m) < v) 40                     l = m;41                 else42                     r = m;43             }44             double x = 2 * tan(r);45             double a = acos(x - 1);46             double s = (pi - a + sin(a) * cos(a)) / sin(r);47             printf("%.5f\n", s);48         }49     }50     return 0;51 }