Pre processors.

Question

Write macro definitions with arguments for calculation of area and
perimeter of a triangle, a square and a circle. Store these macro
definitions in a file called “areaperi.h”. Include this file in your
program, and call the macro definitions for calculating area and
perimeter for different squares, triangles and circles.

Answer 1

Hopefully this will help you get started:
.h file:
#ifndef AREAPERI_H
#define AREAPERI_H
#define AREACIRCLE(A) (3.14 * (A * A))
#endif
.c file
#include "areaperi.h"
#include <stdio.h>
int main(void){
float radius = 2.0;
printf("%5.2f is the area of a circle that has %3.2f radius", AREACIRCLE(radius), radius);
}