题解

#include<iostream>
using namespace std;
int main(){
double a;
cin>>a;
double b=a2;
double PI=3.14159;
double c=a2PI;
double d=aa*PI;
printf("%.4lf",b);
cout<<" ";
printf("%.4lf",c);
cout<<" ";
printf("%.4lf",d);
return 0;
}