思路: 海伦定则,引用sqrt要用头文件#include<math.h> ">#include<math.h> int main(void) { float a=0.0f,b=0.0f,c=0.0f; scanf("%f%f%f",&a,&b,&c); float m=(a+b+c)/2.0; m=sqrt(m*(m-a)*(m-b)*(m-c)); printf("circumference=%.2f area=%.2f",a+b+c,m); return 0; }