shane18 Posted January 7, 2010 Share Posted January 7, 2010 What is the big difference between $radius = 3959 * acos(sin($lat1) * sin($lat2) + cos($lat1) * cos($lat2) * cos($long2 - $long1)); and a2 + b2 = c2 I know it has something to do with the earth not being perfectly sphere... What is the max amount of miles you can go up to with (a2 + b2 = c2) and it is still accurate. Link to comment https://forums.phpfreaks.com/topic/187514-zip-code-search/ Share on other sites More sharing options...
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