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Topic: Trying to find perimeter of a regular pentagon
Replies: 36   Last Post: May 31, 2013 9:26 PM

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Graham Cooper

Posts: 4,253
Registered: 5/20/10
Re: Trying to find perimeter of a regular pentagon
Posted: May 30, 2013 1:33 AM
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On May 29, 1:15 am, 130bcd <carl.sundqu...@gmail.com> wrote:
> Hello,
>
> I have unsuccessfully tried to find the perimeter of a pentagon. The "radius" to the vertices is 130, which I tried to convert into 5 triangles but I can't find a formula for determining the length of the 3rd side of an isosceles triangle.
>
> The two equal length sides would, of course be 130 and the angle between them would be 72.
>
> Help, please!


just use 2 pi r

and don't show too many significant digits!

About 1000!

or use
COS(36) = perim/10 / radius

perim
=
1300 COS(36)
=
1051.7


Herc
--
http://phpPROLOG.com



Date Subject Author
5/28/13
Read Trying to find perimeter of a regular pentagon
130bcd
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
Barry Schwarz
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
Ken.Pledger@vuw.ac.nz
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
Ken.Pledger@vuw.ac.nz
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
David Bernier
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
Brian Q. Hutchings
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/30/13
Read Re: Trying to find perimeter of a regular pentagon
RGVickson@shaw.ca
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
Brian Q. Hutchings
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/31/13
Read Re: Trying to find perimeter of a regular pentagon
Brian Q. Hutchings
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
Brian Q. Hutchings
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
Brian Q. Hutchings
5/28/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/29/13
Read Re: Trying to find perimeter of a regular pentagon
Richard Tobin
5/29/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/29/13
Read Re: Trying to find perimeter of a regular pentagon
Richard Tobin
5/29/13
Read Re: Trying to find perimeter of a regular pentagon
Brian Q. Hutchings
5/29/13
Read Re: Trying to find perimeter of a regular pentagon
JT
5/29/13
Read Re: Trying to find perimeter of a regular pentagon
Brian Q. Hutchings
5/30/13
Read Re: Trying to find perimeter of a regular pentagon
Graham Cooper
5/30/13
Read Re: Trying to find perimeter of a regular pentagon
RGVickson@shaw.ca

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