(x - x0)^2 + (y - y0)^2 <= R^2

   function foo(int $x, int $y){
      $x0 = -2;
      $y0 = 0;
      $radius_min = 1;
      $radius_max = 2;

      if($x >= -1){
        return TRUE;
      }

      $radius = sqrt(pow($x - $x0, 2) + pow($y - $y0, 2));


      return  $radius_min <= $radius && $radius <= $radius_max;

    }