math geo problem

Originally posted by geepamoogle
If the circumference at the longitude 1 km to the north from your starting point is of the form 1/k km, where k is an integer, then taking the path of 1 km North, 1 km West, and 1 km South will bring you back to your starting point. (You'll be in the same place bofore and after the second km travelled.)

I'm sure someone has given the formula for finding these longitudes.

do you mean latitude? i was thinking along the same lines (har har) as this response