"se ttu apri tanto le gam­be che ttu cali da capo 1/14 di tua alteza, e apri e alza le bracia che colle lunghe dita tu tochi la linia della sommita' del capo, sappi che'l cientro delle stremita' delle aperte membra fia il bellico, e llo spazio che ssi truova infra lle gambe fia triangolo equilatero"
Here is an add on to the Vitruvius details, calligraphic by Leonardo Da Vinci at the top of the drawing; on a circular projection which pre­sup­poses, alas, that the arms stretch out more whilst the legs are short­ened, the same ones that have de­ter­mined the square with reliable the­o­ret­i­cal precision.
As we can see, the spread legs in the drawing do not reach the equi­lat­er­al triangulation with the navel; therefore, any other triangle as such, re­sult­ing from the legs positions, is casual and out of symmetry, hence mean­ing­less.
Note that,
should the legs widen enough to really form that triangle, the forced re­duc­tion of distance of the [dark shaded] foot from the cor­rect [red/yellow] arc would be max­i­mum, be­ing on the same sides of the tri­an­gle [gre­en], which align the heads of the femurs to the navel, i.e. their ra­di­us with the center; but the figure could have been less pleasant.
It should be noted alike that this alignment does not mean that the ro­ta­tion of the legs is centered on the navel, what could justify the orig­i­nal de­sign; as well as the rotation of the arms is not centered on the cross­ing of the line of the shoulders with the sternum; which is not re­spon­si­bly ap­pli­ca­ble (more details later), even if sug­gest­ed offhand by the orig­i­nal drawing.
Definitely, the rotations of the limbs have their anatomic trajectories, which cannot be passed over.