Question

Why are line of longitude of the same length?

Answer 1

Are lines of longitude and latitude all the same length. No, they are not. Only the lines of longitude are of equal length. Each line of longitude equals half of the circumference of the Earth because each extends from the North Pole to the South Pole.

Answer 2

All longitudinal lines are of the same length because they are originating from the north and sound polite resulting in them covering half the circumference of earth... all of them