JT
Posts:
1,149
Registered:
4/7/12


Re: Trying to find perimeter of a regular pentagon
Posted:
May 28, 2013 2:53 PM


On 28 Maj, 17:15, 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! http://www.cleavebooks.co.uk/scol/calrtri.htm Here some help with calculation, but no trig function though. I get the height to 67 * 10 to get the perimeter

