# Question...



## javajoe61 (May 31, 2009)

Using landscape timbers for an octogon tree ring. Not sure how long each of the 8 pcs should be at the longest point of the angle (22.5), to have a diameter of 4'. Is there a specific formula for this ?


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## ponch37300 (Feb 27, 2008)

I'm not sure if this is right or not but since no one else has chimed in I thought I would try. I found the circumference of the circle(3.141x2squared) which is 12.564'. Then I divided it by 8 which is 1.57', This isn't going to be a perfect 4 ft in diameter, it will be just a little bigger since 1.57 feet is on the rounded part of the circle and not a straight line like the parts of an octagon but I would think it will be pretty close. If it were me I would cut 2 pieces of 2x4s at 18 1/2" long with 22.5 angles on them and lay them out. When you measure to wards the "center" of the circle(these 2 pieces being 1/4 of a circle) it should be 2' where they intersect. Then you can trim them as needed to get your octagon the exact size you want. Here is a picture to hopefully help out.


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## Streamwinner (Nov 25, 2008)

http://mathcentral.uregina.ca/QQ/database/QQ.09.04/mary1.html


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## javajoe61 (May 31, 2009)

Thanks for the info, this will give me a rough idea_ where to start_. Will tinker with lengths till I get roughly a 4' diameter.

Pete


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## jkristia (Feb 6, 2009)

something like this?, did this quick sketch in AutoCAD.

Jesper


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