Program to draw Polar Ellipse

#include<graphics.h>
#include<conio.h>
#include<iostream.h>
#include<math.h>
#include<stdlib.h>
#include<DOS.h>

void ep(float x,float y,float xc,float yc)
{
putpixel(x+xc,y+yc,RED);
putpixel(-x+xc,y+yc,RED);
putpixel(-x+xc,-y+yc,RED);
putpixel(x+xc,-y+yc,RED);
delay(100);
}

void main()
{
int gd=DETECT,gm;
initgraph(&gd,&gm,"");
cleardevice();
int x, y,xc,yc,xr,yr,theta,theta_end;
cout<<"enter values for xc,yc,xr,yr";
cin>>xc>>yc>>xr>>yr;
theta=0;
theta_end=90;
while (theta<=theta_end)
    {
    x=xr*cos (theta) + xc;
    y=yr*sin (theta) + yc;
    ep(x, y, xc, yc);
    theta=theta+1;
    }
   
    getch();
    closegraph();
}