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38.2 Form of the Earth
38.2.2 Define:
(a) great circles
Great circles are the largest circles that can be drawn on a sphere, dividing it into two equal halves.
They represent the shortest distance between two points on the surface of the sphere.
The equator and any line of longitude are examples of great circles.
(b) small circles
Small circles are any circles on the surface of a sphere that do not divide the sphere into equal halves.
They are smaller than great circles and do not represent the shortest distance between two points.
An example of a small circle is any parallel of latitude other than the equator.
(c) rhumb lines
Rhumb lines, or loxodromes, are lines that cross all meridians at the same angle, representing a constant compass direction.
They are not the shortest path between two points but are useful for navigation as they provide a steady course.