Detecting if location of the user is in a define area in AS3

[Stephdidou]

I've got 7 geolocations points (lat & long) that defines an area like this :

How can I trigger a function when the user is in the area ?

I thought about something like :

if(e.latitude < -20.280442 && e.latitude > -21.414927 && e.longitude < 167.738801 && e.longitude> 166.739045){ 
do something 
}

With this method I'm defining a square (2 latitude points and 2 longitude points).

Do you see another way to do it more precisely ?

[Ned Murphy]

You should be able to create a shape, make its alpha property 0, and then perform hittests to see if the user object is touching that shape.