A386圆的计算•题解

#include<bits/stdc++.h>
using namespace std;
int main()
{
	double r,pi=3.14159,zj,zc,mj;
	cin>>r;
	zj=r*2;
	zc=r*2*pi;
	mj=r*r*pi;
	printf("%.4f",zj);
	cout<<" ";
	printf("%.4f",zc);
	cout<<" ";
	printf("%.4f",mj);
	cout<<" ";
}