C Program to find surface area of a sphere

/*Program to find surface area of a sphere*/

#include<stdio.h>

#define PI 3.14

main()

{

      float r,a;

      printf("Enter the Radius");

      scanf("%f",&r);

      a=4*PI*r*r;

      printf("\n Surface Area of sphere with radius %.2f is %.2f",r,a);

}