Two points within the Arctic Circle are chosen at random, using a uniform distribution over the entire area. That is, any region of a given area is as likely as any other region with that area, to receive a given point.
What is the expected value of their great circle distance from each other?
Assume:
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The Earth is a perfect sphere with radius 3,958.8 miles.
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The Arctic Circle is located at 66.55° North.
Both calculus answers and simulation answers are welcome. As we are using approximations here, especially about the perfect sphericity of the Earth, the exactness of calculus is not really needed.
Part 2:
... and how about two points on the whole Earth?
(In reply to
re(2): soln by Steven Lord)
It is no coincidence that the length of the equator is alkmost exactly 40,000 kilometers. The kilometer was initially defined in 1793 as 1/10000 of the distance between the north (or south) pole and the equator, so all great circles are almost exactly 40,000 kilometers. It would be exact if the earth was perfectly spherical.
re(3): soln
