Trattato dell'architettura
In the second part, Trattato dell'architettura (tractate on architecture) Pacioli discusses in 20 chapters the ideas of Vitruvius on mathematics in architecture.
Pacioli compares the proportions of the human body with architecture, starting from examples in Greek and Roman architecture.
In this part there's a detailed drawing of a human heads.
- Pacioli starts from an equilateral triangle, not coincidentally the first problem in Euclides' book.
- This triangle is fitted into a rectangle.
- In this rectangle a grid is drawn so that eyebrows, nose and lips coincide with the Vitruvian proportions.
In this drawing is the only root appearing in calculations.
There isn't any question of nor . More, Pacioli didn't even know the term golden section.
In other words: Pacioli is bad source to illustrate the use of the golden section in the human body or in architecture.