PHP - Distance Between Two Coordinate Sets (Triangle Distance and Earth Distance)

coordinate-distance.php

<?php
echo triangleDistance(44.977840, -93.258358, 44.973551,  -93.265175);
echo "<br />";
echo "<br />";
echo earthDistance(44.977840, -93.258358, 44.973551,  -93.265175);

    function triangleDistance($startLatitude, $startLongitude, $endLatitude, $endLongitude)
    {
        $kmPerLat = 111.000;

        function getKmPerLongAtLat($lat) {
            $DE2RA = 0.01745329252;
            $lat *= $DE2RA;
            return 111.321 * cos($lat);
        }

        $theta_lat = abs($startLatitude - $endLatitude);
        $theta_long = abs($startLongitude - $endLongitude);

        $dist_lat = $theta_lat * $kmPerLat;
        $dist_long = $theta_long * getKmPerLongAtLat($startLatitude);

        $km = $dist_lat + $dist_long;

        // Convert to Kilometeres
        $miles = $km * 0.621371;

        return $km;
    }


    $KM_PER_MILE = 1.609344;

    function earthDistance($startLatitude, $startLongitude, $endLatitude, $endLongitude)
    {
        $theta = $startLongitude - $endLongitude;
        $dist = sin(deg2rad($startLatitude)) * sin(deg2rad($endLatitude)) + cos(deg2rad($startLatitude)) * cos(deg2rad($endLatitude)) * cos(deg2rad($theta));
        $dist = acos($dist);
        $dist = rad2deg($dist);
        $miles = $dist * 60 * 1.1515;

        $distance = $miles * 1.609344;

        return $distance;
    }