calculate area of a circle in c language | CTechnotips

C program for area of circle

#include <stdio.h>

#define PI 3.141

int main(){

  float r, a;

  printf("Radius: ");

  scanf("%f", &r);

  a = PI * r * r;

  printf("%f\n", a);

  return 0;

}

Mathematical formula for area of circle: 

Here Pie is constant which is equal to

Pie = 22/7 or 3.14159265358979323846264338327950288419716939937510...

Radius is radius of the circle.