#include <stdio.h>

#define PI 3.14159

float areaOfCircle(float radius) {
  float area = PI * radius * radius;
  return area;
} 

int main(void) {
  float r = 3.0f;
  float r1 = 2.0f;
  float area = areaOfCircle(r); 
  printf("areaOfCircle(r) = %f, areaOfCircle(r1) = %f\n", area, areaOfCircle(r1));
  return 0;
}