A Synthetic Method for Representation of Quadric Axes

This essay describes a synthetic method for constructing principal axes starting from any given portion of a quadric surface. This problem, which is one of the classic ones of descriptive geometry, is particularly complex if confronted with graphical representation methods, which is why there are few studies about it. Transposition into space through digital representation has allowed us to develop a simple and rigorous solution, first verified in the case of cones, then extended to all quadrics. The review in space of classic problems of descriptive geometry allowed us also to rework and represent a theoretical solution of the problem given by Otto Wilhelm Fiedler in the second half of the nineteenth century.