提交时间:2026-01-04 15:19:15
运行 ID: 80502
#include<bits/stdc++.h> using namespace std; int main(){ double a; cin>>a; cout<<fixed<<setprecision(4)<<2*a<<" "; cout<<fixed<<setprecision(4)<<2*a*3.14159<<" "; cout<<fixed<<setprecision(4)<<a*a*3.14159<<" "<<endl; return 0; }