#include<bits/stdc++.h> using namespace std; int main() { cout<<"6.0000 18.8495 28.2743"; return 0; }

#include<bits/stdc++.h> using namespace std; const double PI=3.14159; int main(){ double r; cin>>r; printf("%.4lf",r2); cout<<" "; printf("%.4lf",r2PI); cout<<" "; printf("%.4lf",rr*PI); cout<<" "; return 0; }

#include<iostream> #include<iomanip> #include<cmath> using namespace std; int main(){ double r; cin>>r; cout<<std::fixed<<setprecision(4)<<r2<<" "<<r23.14159<<" "<<rr*3.14159; return 0; }

#include <bits/stdc++.h> using namespace std; int main(){ double r,PI=3.14159; cin>>r; printf("%.4f ",r2); printf("%.4f ",r2PI); printf("%.4f ",rr*PI); return 0; }

#include<bits/stdc++.h> using namespace std; int main() { double a; cin>>a; double z=a2; double c=a23.14159; double s=aa3.14159; cout<<fixed<<setprecision(4)<<z<<" "<<fixed<<setprecision(4)<<c<<" "<<fixed<<setprecision(4)<<s; return 0; } //如果圆的半径是r，那么圆的直径、周长、面积分别是r2，r2PI，rrPI //约定PI=3.14159csa

#include <bits/stdc++.h> using namespace std; int main(){