p51第9题

#include<stdio.h>
int main()
{float x,y,a;
printf("请输入x:\n");
scanf("%f",&x);
printf("请输入y:\n");
scanf("%f",&y);
a=((x-2)*(x-2)+(y-2)*(y-2));
if(a<1)
printf("A在圆内");
if(a==1)
printf("A在圆上");
if(a>1)
printf("A在圆外"); 

}