Program to calculate the Area of Circle from co-ordinates of the end points of the Diameter of Circle

//Program to calculate the Area of Circle from
//co-ordinates of the end points of the Diameter of Circle
#include<stdio.h>
#include<conio.h>
#include<math.h>
#define pi 3.1416
int main()
{
  float x1,x2,y1,y2,d,area;
  clrscr();
  printf("Enter the co-ordinates of the Points of Diameter of the Circle\n");
  scanf("%f%f%f%f",&x1,&x2,&y1,&y2);
  d=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1))/2;//To find out the Radius of Circle
  area=pi*d*d;
  printf("The Area of the Circle is = %f",area);
  getch();
  return 0;
}

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