I know this is OT... but I also know that one of you out there can help me... I have a perfect octagon (8-sides)... each of the sides is exactly 21.25" from the corresponding side on the opposite side of the octagon... can anyone tell me (or remind me how to figure out... geometry in high school was sooooo long ago) how long each side will be? any help would be appreciated.

here's what I've got so far... I know that A=B=C... surely there is a way to figure out the length of A, B, and C from the information provided... I just can't remember...

21.25 = L + 2L*sin(45degrees)

I think, where

L is the length of the side in inches
sin = the sine of 45 degrees (on your calculator). edit - cool diagram :)

Message edited on: 01/07/2005 08:55

Dreams are just nightmares on prozac...
Digital WasteLanD

therefore, L = 21.25/(1+2*sin(45degrees))

Dreams are just nightmares on prozac...
Digital WasteLanD

Thanks, Flak... that got me close enough for government work... ;O)

huh...I would have thought every angle on a regular octagon would have been 45 degrees...since it would be 360/8... so then the angle that you show bisected by your midline here would have been 22.5 degrees. That's why I leave math to my brother...the math teacher.

8.3 inches. I opened Rhino (units = cm) and created an octagon with 21.25 cm as half the distance between the edges. Measured one edge, which was 17.60. Ergo, half of that is 8.3. :-) BTW, Claymor, the angle between two edges _is_ 135 degrees. PS. Dem typos.

Message edited on: 01/07/2005 11:32

-- erlik

Attached Link: http://home.att.net/~numericana/answer/geometry.htm#octagon

Lots of fun stuff on this site. The exact same question was asked too.