php : lingkaran

header("Content-Type:image/jpeg");
$background=@imagecreate(100,100);
$kuning=imagecolorallocate($background,250,250,300);
$hitam=imagecolorallocate($background,0,0,0);
imagearc($background,50,50,50,50,0,360,$hitam);
imageJPEG($background);
imagedestroy($background);
?>