Re: formula for great circle computation

From:         Michael Page <>
Organization: Department of Mathematics, Monash University
Date:         13 Oct 95 01:30:20 
References:   1 2 3 4
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Jon Ward <> wrote:
>This question reminds me of a classic mathematics/physics problem, which
>I believe is worth considering :
>I lay a rope around a great circle of the globe. I then lay a second rope
>around the same great circle, but the second rope is ten metres above the
>ground all the way around.
>How much longer is the second rope?

2*pi*(r+10m) - 2*pi*r = 2*pi*10m \approx 62.8m

>Once you have the answer, consider the fact that the last trans-Atlantic
>flight I flew on cruised at 37,000 ft above sea-level.

That's less than ten extra miles compared to the distance if the earth
was flat.  A minute amount compared to that travelled.  So?