public class c {
public double PI=3.1415926;
public void zhouchang(double r){
double l=2*PI*r;
System.out.println("周长:"+l);
}
public void mianji(double r){
double s=PI*r*r;
System.out.println("面积:"+s);
}
public static void main(String[]args){
c a=new c();
a.zhouchang(10);
a.mianji(10);
}
}