Rhino CAD Drawing

[Arctechwelding]

I am new to using the Rhino CAD program and am in the middle of trying to draw an Octagon Fire Pit. I am not able to get all my panel, or side equal it turns out 4 side one length, the other 4 smaller length. The measurements are 49" area x 23" height. I had it pretty close but not sure where i'm going wront on the drawing. Any suggestions welcome, ive tried making i an even number with the same issue.

[djreiswig]

Try this.
http://jwilson.coe.uga.edu/emat6680/par ... const.html