North Point: Center Point: Latitude:   . Longitude:  . SW (240°) Point: SE (120°) Point:
Enter the latitude and longitude (in hdd.ddddd° format) of the Center Point, then click "Calculate". Pad with "0" to the right if you do not have 5 decimal digits of precision. Given these GPS coordinates, this tool calculates the corners of a triad 50 meters from the center, spaced 120° apart.

Assumptions for these calculations:

• Latitude between 41° to 42° N, appropriate for Cook County, IL.
• 1/1000° latitude is about 111 meters, or 1 meter is about .000009°.
• 1/1000° longitude is about 83.5 meters, or 1 meter is about .000012°.
• For the north point, 50 m is about .00045° latitude, simply add the latitude from the center.
• For the 120° point: 50 m is the hypotenuse of a right triangle with 30° and 60° angles.
• The short side (south) is 25 m, or subtract .000225° latitude.
• The long side (east) is 43.3 m, or subtract .000520° longitude.
• For the 240° point: subtract .000225° latitude, add .000520° longitude.
These coordinates can simply be fed to google maps or yahoo maps to locate the plot. Yahoo allows you to use the points as locations in getting "directions" and place them as markers on the map, whereas google can zoom in closer. Here are example maps generated for two triads in Bluff Spring Fen near the northwest boundary of Cook County.

Designed by Peter Chen for Habitat Project.

```Mirrors:
http://www.nicerweb.com/doc/class/pix/LandAudit/GPS_calculator.html
http://www.cod.edu/people/faculty/chenpe/LandAudit/GPS_calculator.html
```