Diameter,Circumference,Area

#include<stdio.h>
#include<math.h>
int main(void)

{
    const float PI=3.1416;
    float r,diameter,circumference,area;
    printf("Enter radius: \n");
    scanf("%f",&r);
    diameter=2*r;
    circumference=2*PI*r;
    area=PI*r*r;
    printf("diameter = %.2f units\n",diameter);
    printf("circumference = %.2f units\n",circumference);
    printf("area = %.2f sq.units\n",area);

}