# include<iostream> # include<iomanip> using namespace std; int main(){ //圆的面积公式：pi*r*r; const double PI=3.1415926; cout<<PI*1*1<<endl; cout<<PI*3*3<<endl; cout<<PI*5*5<<endl; cout<<PI*7*7<<endl; cout<<PI*9*9<<endl; return 0; }