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Article #2807Re: inscribed pentagram...a real puzzle
From: Glenn
Date: Tue, 27 Jul 1999 00:00
Date: Tue, 27 Jul 1999 00:00
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"Jellybean Stonerfish" <stonerfish@tigerlink.net> writes: >I have a circle...Lets say the diameter is one. >What are the lengths of the sides of the following inscribed regular >polygons? >triangle sqrt(3) >square sqrt(2) >pentagon 2*sin(36) >hexagon 1 >7-gon....(my geometry teacher said that the other names are wrong call it a >7-gon ) I've heard it called a septagon or a heptagon. 2*sin(25 5/7) >octagon 2*sin(22.5) >Also is there a simple formula f(x) that you put in the number of sides and >get the lengths of the sides? Yes, 2*sin(180/x) where the angles are measured in degrees. By drawing lines from the center of the circle to two consecutive vertices of the polygon, the side of the polygon is seen to be the third side of a triangle with two sides of length 1 whose inscribed angle is 360/x. By dropping down a perpendicular from the center to get a right triangle; we can use the sine function to get the length of the side.
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 10b299,290fd742f719214f X-Google-Attributes: gid10b299,public X-Google-Thread: 109428,290fd742f719214f X-Google-Attributes: gid109428,public From: rhoads@paul.rutgers.edu (Glenn) Subject: Re: inscribed pentagram...a real puzzle Date: 1999/07/27 Message-ID: <7n6ole$k9d$1@paul.rutgers.edu> X-Deja-AN: 506038064 Distribution: inet Approved: approve Sender: approve@forum.swarthmore.edu References: <C9wl3.406$R5.3165@newsfeed.slurp.net> To: geometry-puzzles@Rutgers.EDU Organization: Rutgers University LCSR Newsgroups: rec.puzzles,geometry.puzzles