Simple Geosearch in Laravel

Post.php

/**
     * Scope to query the database to return the listings between
     * a latitude and longitude, with distance.
     *
     * @param \Illuminate\Database\Eloquent\Builder $query
     * @param Double $lat
     * @param Double $lng
     * @param Integer $radius - KM
     * @return \Illuminate\Database\Eloquent\Builder
     */
    public function scopeAroundLatLng($query, $lat, $lng, $radius)
    {
        // earth's radius in km = ~6371
        $earth_radius = 6371;

        // latitude boundaries
        $maxlat = $lat + rad2deg($radius / $earth_radius);
        $minlat = $lat - rad2deg($radius / $earth_radius);

        // longitude boundaries (longitude gets smaller when latitude increases)
        $maxlng = $lng + rad2deg($radius / $earth_radius / cos(deg2rad($lat)));
        $minlng = $lng - rad2deg($radius / $earth_radius / cos(deg2rad($lat)));

        return $query->whereBetween('lat', [$minlat, $maxlat])->whereBetween('lng', [$minlng, $maxlng]);
    }