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Symbol | Definition |
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≡ | exactly equal |
≈ | approximately equal to |
= | equal to |
digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |
Earth radius is the distance from Earth's center to its surface, about 6,371 km (3,959 mi). This length is also used as a unit of distance, especially in astronomy and geology, where it is usually denoted by R⊕.
A metric mile is a distance which approximates one statute mile (1609.344 m) at a round figure of metres (the SI or metric unit of length). The term is most commonly used in track running and swimming.
In track running, the 1500 m race became the standard middle distance race in Europe in the late 19th century, and has been the standard distance in the Olympic Games since 1896. The distance of the race is sometimes referred to as a metric mile.