一、运行结果；

二、源代码；

# define _CRT_SECURE_NO_WARNINGS
# include <stdio.h>
# include <math.h>int main()
{//初始化变量值；double a, b, c, s, area;//赋值；a = 3.67;b = 5.43;c = 6.21;//运算求s；s = (a + b + c) / 2;//运算求面积；//sqrt函数式开根号函数；area = sqrt(s * (s - a) * (s - b) * (s - c));//输出结果；printf("a = %f\tb = %f\tc = %f\n", a, b, c);printf("三角形的面积 area = %f\n", area);return 0;
}

三、N-S流程图；