#include <stdio.h>
#define PI 3.14159f // Definition of the symbol PI
int main(void){
float radius = 0.0f;
float diameter = 0.0f;
float circumference = 0.0f;
float area = 0.0f;
printf("Input the diameter of a circle:");
scanf("%f", &diameter);
radius = diameter/2.0f;
circumference = 2.0f*PI*radius;
area = PI*radius*radius;
printf("\nThe circumference is %.2f. ", circumference);
printf("\nThe area is %.2f.\n", area);
return 0;
}