Using the Lat&Lon Coordinate System
Latitude
Lines of latitude measure north-south position between the poles. The equator is defined as 0 degrees, the North Pole is 90 degrees north, and the South Pole is 90 degrees south. Lines of latitude are all parallel to each other, thus they are often referred to as parallels.
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It is used as a key to measure distance
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One degree of latitude is 60 nautical miles, 69 statute miles or 111 km.
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One minute of latitude is 1 nautical mile, 1.15 statute miles, or 1.85 km.
Longitude
Lines of longitude, or meridians, run between the North and South Poles. They measure east-west position. The prime meridian is assigned the value of 0 degrees, and runs through Greenwich, England. Meridians to the west of the prime meridian are measured in degrees west and likewise those to the east of the prime meridian are measured to by their number of degrees east.
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Decimal & Degree Conversion
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It is seldom necessary to convert from minutes and seconds to decimals or vice versa; however, if you use the function tables of many trade manuals, it is necessary. Some tables show the fractions of degrees in minutes and seconds (DMS) rather than decimals (DD).
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Tutorial Link: http://mathforum.org/sarah/hamilton/ham.degrees.html
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