Final answer:
A planar projection is a type of map projection where a straight line represents the shortest distance between two points on Earth's surface. Great circles, such as the equator and meridians, provide the shortest paths and are central to understanding planar projections.
Step-by-step explanation:
A planar projection shows the Earth centered in such a way that a straight line coming from the center to any other point represents the shortest distance.
When talking about planar projections, we refer to map projections that display the surface of the Earth onto a flat plane. For example, in Mercator projections, a form of cylindrical map projection, which present the globe as if it has been wrapped around a cylinder, all latitude lines are the same length as the equator. Great circles, which are the circles that pass through the center of the Earth and divide the globe into equal halves, provide the shortest distance between two points on the surface of the Earth. The equator and the meridians are examples of great circles.
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