5543 = 2 x ∏ x 6400 x cos a

cos a = 0.1378

a = 82

so it woudl be the 82°N and the 82°S (this is approx since i have rounded)

the 90 parallel, which are the two poles (and they are points, having no distance) is zero and this is becasue it woudl be of this form

L = 2 x ∏ x 6400 x cos 90 and cos 90 = 0

hope that is what you are after

jacs