Diameter, Circumference and Area of Circle in C

The mathematical formulas behind these calculations are:

Diameter of a Circle = 2r = 2 * radius

Circumference of a Circle = 2πr = 2 * π * radius

Area of a circle is: A = πr² =  π * radius * radius

#include<stdio.h>
#define PI 3.142
int main()
{
	float radius, area, circumference, diameter;

	printf("Enter radius of circle : ");
	scanf("%f",&radius);

	diameter = 2 * radius;
	circumference = 2 * PI * radius;
	area = PI * radius * radius;

	printf("Diameter = %.2f\n", diameter);
	printf("Circumference = %.2f\n", circumference);
	printf("Area = %.2f\n", area);
}