Creating a geo point from another and a distance. Means adding distance to geo point

GeoOffsetByDistance.php

<?php
/**
 * Class GeoOffsetByDistance
 */
class GeoOffsetByDistance
{
    //Earth’s radius, sphere in meters
    const R = 6378137;

    /** @var float */
    private $lat;
  
    /** @var float */
    private $lon;

    /**
     * GeoDistanceHelper constructor.
     *
     * @param $lat
     * @param $lon
     */
    public function __construct($lat, $lon)
    {
        $this->lat = $lat;
        $this->lon = $lon;
    }

    /**
     * @param $meters
     * @return array
     */
    public function offset($meters)
    {
        define('PI',pi());

        //offsets in meters
        // a² = b² + c² with b = c
        // a² = b² + b² => a² = 2b² => b = a * sqrt(2)
        $dn = $meters / sqrt(2);
        $de = $meters / sqrt(2);

        //Coordinate offsets in radians
        $dLat = $dn/self::R;
        $dLon = $de/(self::R*cos(deg2rad($this->getLatitude())));

        //OffsetPosition, decimal degrees
        $latO = $this->getLatitude() - rad2deg($dLat);
        $lonO = $this->getLongitude() - rad2deg($dLon);

        return ['lat' => $latO, 'lon' => $lonO];
    }
  
  /** @return float */
  public function getLatitude()
  {
      return $this->lat;
  }

  /** @return float */
  public function getLongitude()
  {
      return $this->lon;
  }
}