Answer:
40,000 km
Step-by-step explanation:
The circumference is given by the formula ...
C = 2πr
For the given values of π and radius, the circumference is ...
C = 2·3.14·6400 km = 40,192 km
Rounded to the nearest 10,000, the length of the equator is 40,000 km.
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Additional comment
The original definition of the meter was 1/10,000,000 of the distance from the north pole to the equator, through Paris. Essentially, the polar circumference of the earth was defined as about 40,000 km. The polar distance in the southern hemisphere will differ from that in the northern hemisphere, and apparently, the chosen longitude also makes a difference. All of these are different from the equatorial circumference. That definition has long been superseded.
