# what is the relevance of cosine in determining map resolution? [closed]

"At any latitude and zoom level, you can determine the scale by using the following equation"

``````Map resolution = 156543.04 meters/pixel * cos(latitude) / (2 ^ zoomlevel)
``````

is a quote from (http://msdn.microsoft.com/en-us/library/aa940990.aspx)

Can anyone explain to me the relevance of the cos(latitude) part? I am having difficulties visualising this.

## closed as off-topic by BradHards, Fezter♦, PolyGeo♦, Paul, Jason ScheirerMar 24 '14 at 5:54

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• - ok so it´s simply the ratio used to calculate the length of the distance from 0° Longitude to the tangent of the sphere, thus giving the resolution at the given latitude. – Robert Buckley Mar 22 '14 at 7:40
• How about adding that as an answer? – raykendo Mar 23 '14 at 3:20

## 1 Answer

• ok so COSINE is simply the ratio used to calculate the distance from 0° Longitude (i.e. the center of the shpere) to the tangent of the sphere at a given latitude. This site helped me understand the concept.

http://www.mathsisfun.com/sine-cosine-tangent.html
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