
Re: Trying to find perimeter of a regular pentagon
Posted:
May 30, 2013 1:33 AM


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

