Great Circles

  • Thread starter lbass
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Could somebody please please explain how to work out the minimum distance between two co-ordinates on the earth, eg hobart(43 S,147 E) to Beijing (39 N, 117 E). Apparently there is a method incorporating great circles which finds min distant. If anyone knows the formula and could give me a quick explanation, would be much appreciated.
Cheers
 

Answers and Replies

  • #2
HallsofIvy
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Yes, the shortest distance between two points on the surface of a sphere is along a "great circle" which is a circle having the center of the sphere as its center. The length of an arc of radius R and subtending central angle [itex]\theta[/itex], in radians, is R[itex]/theta[/itex]. If [itex]\theta[/itex] is in degrees that is [itex]R\theta (\pi/180)[/itex]. Here R is the radius of the earth and you will need to work out the angle [itex]\theta[/itex] from the latitude and longitude.
 

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