Distance: CR4 Challenge (04/22/08)

I do have to agree, the question leaves a lot of holes in it. The pump problem had fewer leaks in it than this one. Ha-Ha-Ha

Gadgetman...with due respect;

Today you are the statue...

nuff said

That's a really cool drawing, what did you use ?

Re the angle;

Ø = (9000/(2.Π.3959)) x 360^o

You're quite correct, but it's easier to think of the arc as a fraction of the full (ie 360) circle.

That's a really cool drawing, what did you use ?

Re the angle;

Ø = (9000/(2.Π.3959)) x 360^o

You're quite correct, but it's easier to think of the arc as a fraction of the full (ie 360) circle.

I used AutoCAD 2007.

Drawing lines in AutoCAD at known angles is easier than drawing an arc of a known length, if you have polar tracking turned on. I knew the arc length, and the radius. If I drew the radius lines first, then all I needed was the angle between them to get the proper arc length.

If you wish, I can add a post describing what I did.

I'm surprised no one responded to my Star Wars comment. I though for sure there were enough geeks on here that someone would say something. Guess I should have mentioned Seven of Nine instead...

Thanks for the offer of more info, but not being a CADdict, it would be lost on me !

Guess I should have mentioned....

Oh, no....Someone was sure to do it sooner or later !

I manipulated to solve for Θ, and came up with an angle of roughly 130°.Nice,very NICE.

I was expecting to create a somewhat dome-shaped "slice" of the Earth. The peak of the dome would be city B, and the edge would be a circle described by radius of 9000 miles from B along a great circle path.awesome,nice intuition ,it give me a though ,if ...it is your part.

The challenge question's conclusion is correct.

The explanation is wrong.

It's certainly not as clear as it could be - and there are inconstisencies between the main text ("anywhere from 0 to 6900 miles") and the text on the drawing. Would you agree that if we alter the text on the drawing (from "only two possile locations of C") to match the main text (e.g. "extreme possible locations of C") we would have a reasonable explanation?

'Wrong' is 'wrong'. If a better/clearer analysis emerges in the answers from participants, the official answer should acknowledge that; "The intended official answer was "************", but readers are recommended to the solutions offered at #XX". The 'Good Answer' system goes some way to resolving that, but in this case the official answer is flawed. I see no problem with some retraction on the official answer, given the level of expertise available to propose answers on CR4. I shall go back an ensure I have voted for some of the excellent answers given to this question. This question emphasizes that it pays to read all contributions.

If referring to a flat disc,...but what if the cities were on a planet that was a sphere?

That drawing would be wrong for a disc - as (presumably) you could take the straight-line routes from B to A and from B to C. It must be intended to show the furthest-apart and coincident routes on a great circle.

The official answer would have benefited by the addition of a note or label stating that the illustration was a cross-section of the earth.