Create a square around a latitude and longitude based on a distance in meters in PHP

lat_long_square.php

$distance = 30000;
$radius_of_earth = 6335000;

$longitude_offset = ($distance / $radius_of_earth) * (180 / pi()) / cos(($latitude * pi())/180);
$latitude_offset = ($distance / $radius_of_earth) * (180 / pi());

$max_longitude = $longitude + $longitude_offset;
$min_longitude = $longitude - $longitude_offset;
$max_latitude = $latitude + $latitude_offset;
$min_latitude = $latitude - $latitude_offset;