#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout << acos(-1) << endl;
return 0;
}
运行结果如下:
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout << acos(-1) << endl;
return 0;
}
运行结果如下: