Longitudes and Latitudes

JonB

JonB

JonB

Associate
Joined
3 Oct 2006
Posts
2,304
Location
London
Hi There,

I'm playing with longitudes and latitudes and wondering if you maths folk know of a standard formula that would give you the distance between one long and lat and another long and lat, as the crow flies?

Thanks
 
Ricochet J said:
Isn't it:

AC = sqrt ((A-B)sq+ (B-C)sq)

Where sqrt stands for square root and sq stands for squared.
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No, that only works for flat surfaces. The surface of the earth is very definitely curved. The page Haircut linked to has the correct formula for distances on the surface of a sphere.
 
KaHn said:
Surely just use the length of an arc

L=(theta)*r

Where r = radius of the earth and the (theta is the angle between the longs and lats in radians.

KaHn
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Works if you happen to know the angle between the two coordinates you're interested. Unfortunately, unless they're at the same latitude or longitude then you have to do some extra maths first. Much easier just to use the analogue of Pythagoras' theorem for spherical surfaces.
 
Arcade Fire said:
Works if you happen to know the angle between the two coordinates you're interested. Unfortunately, unless they're at the same latitude or longitude then you have to do some extra maths first. Much easier just to use the analogue of Pythagoras' theorem for spherical surfaces.
Click to expand...

Yeah sorry, i didn't read fully and just thought he meant distances in a straight line, say lat 20 to lat 40 distance.

KaHn
 
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