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Topic: Have I gone insane? Myth-busting pentagons by compass & straight edge.
Replies: 45   Last Post: Aug 18, 2013 5:55 PM

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 Wayne Bishop Posts: 4,975 Registered: 12/6/04
Re: Have I gone insane? Myth-busting pentagons by compass & straight edge.
Posted: Aug 9, 2013 2:24 AM

At 07:18 PM 8/8/2013, GS Chandy wrote:
>Jonathan Crabtree posted Aug 9, 2013 3:55 AM:
> >
> > Can a regular pentagon with five identical side
> > lengths and five internal angles of 72Â° be inscribed
> > on a circle with compass and straight edge only?
> >

>Surely the 'internal angles' of a pentagon have
>to be each 108Â° and not 72Â°?

By 'internal', I'm sure he meant central angles
that subtend but there's another, a little less
obvious but, cute idea as well; the exterior
angle of a regular n-gon is also 360/n.

Wayne

Date Subject Author
8/9/13 Jonathan Crabtree
8/8/13 GS Chandy
8/15/13 Wayne Bishop
8/9/13 Jonathan Crabtree
8/15/13 Wayne Bishop
8/9/13 Jonathan Crabtree
8/10/13 Wayne Bishop
8/11/13 Wayne Bishop
8/10/13 Joe Niederberger
8/10/13 GS Chandy
8/9/13 GS Chandy
8/15/13 Wayne Bishop
8/10/13 Joe Niederberger
8/10/13 GS Chandy
8/11/13 Joe Niederberger
8/11/13 Wayne Bishop
8/11/13 GS Chandy
8/12/13 Joe Niederberger
8/12/13 Wayne Bishop
8/11/13 GS Chandy
8/12/13 Joe Niederberger
8/12/13 Joe Niederberger
8/12/13 Robert Hansen
8/15/13 Joe Niederberger
8/12/13 GS Chandy
8/14/13 Joe Niederberger
8/14/13 GS Chandy
8/11/13 Joe Niederberger
8/11/13 GS Chandy
8/12/13 Joe Niederberger
8/12/13 GS Chandy
8/14/13 Joe Niederberger
8/14/13 GS Chandy
8/12/13 Joe Niederberger
8/12/13 GS Chandy
8/10/13 Joe Niederberger
8/11/13 GS Chandy
8/11/13 Wayne Bishop
8/12/13 GS Chandy
8/16/13 GS Chandy
8/17/13 kirby urner
8/17/13 Joe Niederberger
8/17/13 kirby urner
8/18/13 kirby urner
8/18/13 Wayne Bishop
8/18/13 GS Chandy