12 hours, the shortest route is to fly to the North Pole and then fly north and south. A * * * spans 60 longitude, and the latitude difference is 1 degree, so the difference is11km, and the flight distance is = (90-60) * 2 * 1 1, divided by 8 hours.

If you fly along the north latitude of 60, and just fly to the latitude of 1 80, the longitude difference on the equator is1degree difference1km, and 60 degrees is half of the equator, so it is (100+80) */kloc-.