Prove that the length of any parallel of latitude is equal to the length of the equator times the cosine of the latitude angle.
Assume as an approximation that the earth is a perfect sphere.
Call the radius of the sphere r.
Using the formula for the circumference of a circle, the length of the equator is `2pir`
Now, draw a triangle with a point at the centre of the earth A, a point on a particular latitude line B and a point horizontally across from that directly above the...
(The entire section contains 191 words.)
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