Non-Euclidean geometry and the Pythagorean Theorem

[Feadel]

I just learned this in my Trig. class this last semester. Unfortunately, since the semester is over, I've forgotten it all already.
In answer- Yes there is a way, using trigonometry, to calculate that. But I don't remember the specifics and I don't have a book. You might try google for trig or spherical measurements.

[Hai-Etlik]

Well, assuming a sphere, the answer is here: http://en.wikipedia.org/wiki/Great-circle_distance

It gets more complex if you want to use a spheroid, and really complex if you want to use the geoid.

Another option is to use an Equidistant Azimuthal projection centred at one of the endpoints, all distances along lines through that point will be true.

PS: Also, a circumference of 3491.86 miles gives a radius of 894.29 km, That's incredibly tiny. Earth has a mean radius of 6,371.01 km.

Assuming similar density, and that I got my math right, that should mean it has about 1/7 of Earth's surface gravity.