[aprssig] A math problem concerning Lat and Long
Curt Mills archer at eskimo.comWed Oct 6 04:33:24 UTC 2004
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On Tue, 5 Oct 2004, Wes Johnston wrote: > For close in distances, I count 1 degree north-south as 69statute > miles.... of course one degree east-west is subject to the COS of the > latitude. Entirely as a quick approximation, I average the two lat's > and use that average in my COS(lat) x 69 miles x X number of degrees. > From there, it's Pythagorean Theorem.... z^2=x^2+y^2 > > Again, this is only for a close in approx... I have checked this method > and it's good to <0.1 mile at 100 miles, which was good enough for me. Of course the absolute easiest way of computing distances like this is to switch to UTM coordinates. Then everything is in meters, and the theorem above works great... Until you get near the edge of a zone and have to cross zone boundaries that is. Usually a non-issue though. -- Curt, WE7U. archer at eskimo dot com http://www.eskimo.com/~archer Lotto: A tax on people who are bad at math. - unknown Windows: Microsoft's tax on computer illiterates. - WE7U. The world DOES revolve around me: I picked the coordinate system!"
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