It is the division of the globe measured in degrees East & West of the Prime Meridian, 0 degrees, which is a line running North to South from the North to South Pole through Greenwich, London. the reason Greenwich was chosen was it was the HQ of the Admiralty, the Royal Navy. Latitude could be more easily measured by the elevation of the sun, but Longitude was originally more difficult to actually measure. 180 degrees E & W is the location, mostly, of the International Date Line & runs through the Pacific Ocean..
The longitude of a place is the angle of the shortest arc on the
Earth's surface between the place and the Prime Meridian.
The latitude of a place is the angle of the shortest arc on the
Earth's surface between the place and the Equator.
longitudes is the east to west straight line
The longitude of a place is the angle of the shortest arc on the
Earth's surface between the place and the Prime Meridian.
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