Frank A Cahoy k0blt@juno.com asked
A friend and I were discussing the actual physical size of a grid square in kilometers and or miles and we cannot come up with anything positive. Can anyone reading this provide us with those actual numbers? No real argument involved. Just a matter of curiosity..... Thank you in advance...
1 degree of latitude = 60 minutes = 60 nautical miles (by definition)
1 nautical mile = 1.852 kilometers (by definition)
1 degree of latitude = 60 * 1.852 = 111.12 km
1 degree of longitude = 60 * 1.852 * cos(latitude) kilometers
At the equator, a grid square is approximately 222 by 111 kilometers.
At 60 degrees north a grid square is approximately square, because cos(60) = 0.5
If you want to bore people at parties, geometry on a sphere, with great circles for lines, is an example of a Riemannian geometry, where (among other things) the sum of the angles in a triangle always exceeds 180 degrees.
Laura Halliday VE7LDH "Que les nuages soient notre Grid: CN89mg pied a terre..." ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte
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