Elements of the doctrine of solids
Euler presents several results relating the number of plane angles of a solid to the number of faces, edges, and solid angles. The main theorem is that in all solid bodies confined by planes, the sum of the number of solid angles and the number of faces is two less than the number of edges. Euler also classifies polyhedra by the number of solid angles they have.
Original Source Citation
Novi Commentarii academiae scientiarum Petropolitanae, Volume 4, pp. 109-140.
Opera Omnia Citation
Series 1, Volume 26, pp.71-93.