I have the following program

After the instructions I would like to have the following function to compute the surface area of a cylinder. My teacher is instructing me to have to call the function from MAIN. How do I do this?Code:#include <math.h> #include <stdio.h> #define PI 3.14159 /* Function prototypes */ void instruct(void); /* * Displays instructions to a user of program to compute the * area and circumference of the open-top cylindrical * container. */ void instruct(void) { printf("This program determines the cost of producing an\n"); printf("open-top cylindrical container.\n\n"); printf("To use this program, we first must determine the\n"); printf("radius of the base of the open-top cylindrical container\n\n"); printf("So please enter the radius of the base after the prompt:\n"); } int main(void) { instruct(); return(0); }

Code:#include <math.h> #include <stdio.h> #define PI 3.14159 int main(void) { double radius; double height; double surface_area; double base; double length; printf("Enter radius > "); scanf("%lf", &radius); printf("Enter the height > "); scanf("%lf", &height); base = (PI * pow(radius, 2)); length = (2.0 * PI * radius) * height; surface_area = base + length; printf("The surface area is %5.2f.\n", surface_area); return(0); }