关于c语言学习中存在的问题

Question

include

include

double get_area(double x,double y,double z)
double main
{
double a,b,c;
a=3.0;
b=4.0;
c=5.0;
area=get_area(a,b,c);
printf("the area of this triangle is:%lf\n",area);
return 0;
}
get_area(double a,double b,double c)
{
double area,s;
s=(x+y+z)/2;
area=sqrt(s*(s-x)*(s-y)*(s-z));
return area;
} 想根据三边关系计算三角形的面积，: fatal error C1083: Cannot open include file: 'math,h': No such file or directory这是错误信息，希望大神指导