atan(正切函数)

atan函数：返回数值的余切值

原型：double atan(double x) 

#include
#include
using namespace std;
int main()
{
	double PI = 4.0*atan(1.0);
	double r;
	while(cin>>r)
	{
		cout<<"PI = 4.0*atan(1.0) = "<
 
   
 
   
 
   
 
   
 
   
 
   
 
  

转载于:https://www.cnblogs.com/NYNU-ACM/p/4248791.html