Finding out if a LngLat point is between two other Points

Question

Construct a polyline between the original two points. Then use the isLocationOnEdge function to determine if the 3rd point is within a certain number of degrees from your polyline.

e.g.

<!DOCTYPE html>
<html>
<head>
<title>Is a point within x degrees of a polyline</title>

<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<style type="text/css">
html { height: 100% }
body { height: 100%; margin: 0; padding: 0 }
#map_canvas { width:100%; height:100%; }
</style>
<!-- need to load the geometry library -->
<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?libraries=geometry&sensor=false"></script>

<script type="text/javascript">
    function initialize() {
        var latlng = new google.maps.LatLng(54.5003526, -3.0844116);

        var myOptions = {
            zoom: 10,
            center: latlng,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        var map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);

        var marker = new google.maps.Marker({
            position: latlng,
            map: map, 
            title: "foo"
        });

        var latLng1 = new google.maps.LatLng(54.60039, -3.13632);
        var latLng2 = new google.maps.LatLng(54.36897, -3.07561);

        var polyline = new google.maps.Polyline({
            path: [latLng1, latLng2],
            strokeColor: "#FF0000",
            strokeOpacity: 1.0,
            strokeWeight: 2,
            map: map
        });

        console.log(google.maps.geometry.poly.isLocationOnEdge(latlng, polyline));
        console.log(google.maps.geometry.poly.isLocationOnEdge(latlng, polyline, 1));
        console.log(google.maps.geometry.poly.isLocationOnEdge(latlng, polyline, 0.1));
        console.log(google.maps.geometry.poly.isLocationOnEdge(latlng, polyline, 0.01));
        console.log(google.maps.geometry.poly.isLocationOnEdge(latlng, polyline, 0.001));
        console.log(google.maps.geometry.poly.isLocationOnEdge(latlng, polyline, 0.0001));
        console.log(google.maps.geometry.poly.isLocationOnEdge(latlng, polyline, 0.00001));
    }

    google.maps.event.addDomListener(window, 'load', initialize);
</script>

</head>
<body>
    <div id="map_canvas"></div>
</body>
</html>

Doing this I can see my point is within 0.1 degree from my line, but it's not within 0.01 degree of it. Your tolerance in degrees will vary depending on situation.