题解 2768: 与圆相关的计算

解题思路:

注意事项:

参考代码:

#include<stdio.h>

int main()

{

double pi = 3.14159;

float r = 0;

double zhijin, zhouchang, mianji;

scanf("%f\n", &r);

zhijin = 2 * r;

zhouchang = 2 * pi * r;

mianji = pi * r * r;

printf("%.4lf %.4lf %.4lf", zhijin, zhouchang, mianji);

return 0;

}