**Question**: What is the distance traveled by a plane that goes around the earth at the latitude of 60 degrees?

**Answer**: The formula for the distance traveled around the earth at a particular latitude is

C=2 x pi x r x cos (a)

where

pi is 3.14159,

r is the radius of the earth which is 6278 kilometers,

cos(a) is the the cos of the angle of latitude.

Note that at the equator the latitude is 0 degrees and the cos(0) is 1 so the distance traveled is 2 x 3.14159 x 6278, which is 40,074 km.

Note also that at the poles the angle of latitude is 90 degrees, the cos(90)=0 and the distance traveled is 0.

The question asks for the distance traveled at a latitude of 60 degrees. The cos(60) is 0.5.

So at 60 degrees latitude the distance traveled around the earth is 20,037 km.

**Information on this formula was obtained from a Department of Energy Web site: See citation below:**

Richard E. Barrans Jr., Ph.D.

Assistant Director

PG Research Foundation, Darien, Illinois

The answer was posted on a web site created by National Argonne Labs

**Here are web sites providing some information on cities that are a latitude of 60 degrees north**

**Interestingly there is no land at 60 degrees south**

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