A triangular pyramid
This drawing, attributed to Leonardo da Vinci and taken from the plates of Luca Pacioli's "De divina proportione" shows a triangular pyramid.
© Archivi Anthelios
The image belongs to the sections...:
The polyhedra of Leonardo da Vinci for Luca Pacioli (3D geometry)
Prisms, antiprisms, pyramids, dipyramids (3D geometry)