Quite right, Haversine it is. When I wrote this though accuracy is what I had in mind because of the type of application it was powering and the data we were getting was extremely accurate, or so the client claimed (without a GPS who am I to say it was not accurate!) since they were paying an astronomical amount of money for this and other GeoSpatial data.
I agree that the Pythagorean theroem is the way to go if accuracy is not of the utmost importance and, as you said, it is less resource intenstive.
As with anything in programming there is more then one way to solve a problem and I think that both solutions presented here achieve that with varying pros and cons.
Read this if you want to know how to get a correct reply for your question:
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