### Eratosthenes

How to convert latitude in different systems?

#### From decimal to degree-minute-second

The angular results (Angle at Top, Latitude and Longitude Converter) you must input on your results form must be presented under the form degree-minutes-second.

If you wish to make the conversion manually you just have to do the following procedure where we will use the decimal latitude of 38.1564º (38.1564) as an example:

1) The integer part is the degrees. In our example, 38º.

2) Multiply the decimal part by 60. The integer part of this result is the minutes component of the angle. In our example, this operation (0.1564 × 60 = 9.384) tells us that the minutes component is 9'.

3) Multiply the decimal part of the previous operation by 60. The integer part of this result is the seconds component of the angle.In our example, this operation (0.384 × 60 = 23.04) tells us that the seconds component is 23''. The precision of our measurements gives no significance to the 0.04'' and therefore it can be ignored.

4) You have now you angle in degrees-minutes-seconds. In our example it was 38º09'23''.

#### From degree-minute-second to decimal

For most of your distance calculations and perimeter estimation, it is better to use the decimal latitude. If you used Goggle Maps this is the data that you extracted from the "ll" parameter.

If you used a GPS, the you have the latitude in the form degrees-minutes-seconds. To convert this value to a decimal form you just have to do the following calculation:

latitude (decimal) = degrees + minutes/60 + seconds/3600

For instance for the latitude 38º09'23''N we should have

latitude (decimal) = 38 + 9/60 + 23/3600 = 38.1564º

If it was a northern hemisphere latitude it should be used as it is, but since it is a southern hemisphere latitude it should be marked as negative. The decimal latitude is therefore -38.1564º.