I thought that you might be interested in some earlier references to this construction that I came across in an addendum to "The Geometer's Angle No. 4: From Pentagon to Heptagon:A Discovery on the Generation of the Regular Heptagon from the Equilateral Triangle and Pentagon" by Mark A Reynolds alias "Marcus the Marinite". The original article was published in NEXUS NETWORK JOURNAL VOL. 3, NO 2, 2001, and having found the addendum online some time ago it no longer seems to be available so I can't give a link.

Mark Reynold's points out that the contsruction is found in the book "Geometrica Deutsch" probably published by Roriczer ca. 1472-1484. So it exists 50 years before the 1525 publication of "Underweysung der Messing mit Zirkel und Richtscheit" (Treatise on Mensuration with Compass and Ruler) by Dürer, in which this drawing can be found. It also subsequnetly appears in "La pratica della perspettiva" by Daniele Barbaro published 1569.

His construction of a heptagon is also worth exploring.

many thanks for the note. I have amended the page.

Alex