Convert activity3.c below to a multi-file c program with 3 files: activity3.c, mymath. h, and mymath. c. give the gcc command to build the new program. don’t forget the include guards! when you are done, copy each file to this document in the appropriate place.
/* activity 3 - create a header file */
#include
#define pi 3.14159
int square(int x) {
return x * x;
}int main() {
int radius;
double area;
printf("enter the radius: ");
scanf("%d", & radius);
area = pi * square(radius);
printf ("the area of a circle with radius %d is %.2f\n", radius, area);
return 0;
}