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Euclid Revisited Mystery Cache

Hidden : 12/22/2005
Difficulty:
3 out of 5
Terrain:
3.5 out of 5

Size: Size:   regular (regular)

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Geocache Description:

A multi-part cache involving some problem solving and a good long hike. Located in Manchester Woods.


Hope you saved your compass and straight edge from 9th grade geometry, because you're going to need them. I got the inspiration for this cache from Euclid's Revenge: a cache which gives three vertices of a triangle and asks you to search at its circumcenter. I seemed to recall that there were at least three or four different ways to define the center of a triangle and did a little research to verify. It turns out that mathemeticians have thought of at least 13 ways to define the center of a triangle, though most of them are pretty esoteric. (see reference page) Anyhow, I thought I would incorporate this little geometry lesson into a cache.

Below are three sets of coordinates:

N 42 36.528, W 070 47.101
N 42 36.376, W 070 46.488
N 42 35.072, W 070 48.072

This set defines a triangle. At each of the following three centers you will find a micro containing a part of the clue to the final cache:

The Centroid
The Circumcenter
The Incenter

The centroid represents the effective center of mass of the triangle. The circumcenter is the point that is equidistant from the three corners of a triangle. The incenter is the center of a circle inscribed in the triangle, tangent to the three sides. You could find these centers using a compass and straight edge on a map, or using a drafting or mapping program on a computer. (check the reference page to find out how) Use Caution! Only one of the above centers is insensitive to a stretching transformation, so do not assume the coordinates represent a regular grid or you will not find the other two! My best efforts on paper have resulted in an accuracy of 20-30 feet, which I believe is adequate. When you get coordinates, feel free to email them to me for verification before striking out.

The coordinates listed for this cache are the recommended parking spot. If you're not familiar with the area, I suggest you have a look at the map before you start. You can warm up by visiting the boardwalk cache which is nearby. Be prepared to copy down the clues as you find them. There will be at least 4 miles of hiking over difficult terrain, so expect to spend at least 2-3 hours. Heavy snow could make this tricky, but not impossible. Once you get all the clues, stop and think about it for a minute. You should be able to find the cache on the spot without doing any complicated calculations.

Hope you enjoy the hike in what I think is a beautiful piece of woods.

Additional Hints ()

[Calculations:] Punatr gur pbbeqvangrf gb HGZ. Guvf pna or qbar bayvar naq jvyy znxr guvatf zhpu rnfvre. (HGZ vf n erthyne tevq zrnavat lbh pna hfr fgnaqneq trbzrgevpny grpuavdhrf) [Circumcenter:] Fgrc hc naq crrx va gur penpxf. [Centroid:] Gerr jvgu n ohey. [Incenter:] Xnvea'g lbh svaq vg? [Cache:] Jrfg fvqr, oruvaq n ybaryl reengvp.

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)

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