31. Descriptive geometry and projective geometry are introduced at age 15 / 16 and 16 / 17, respectively. 32. This phenomenon is axiomatized in projective geometry . 33. Furthermore, this approach extends to include plane " at infinity ", in the sense of projective geometry . 34. It is a part of the fundamental theorem of projective geometry that the two definitions are equivalent. 35. When the opportunity to teach projective geometry at the military academy in Turin arose, Pieri moved there. 36. The term " geometric algebra " was used by E . Artin for matrix methods in projective geometry . 37. Affine geometry is one of the two main branches of classical algebraic geometry, the other being projective geometry . 38. The usual definition of a conic uses a quadratic form ( see Quadric ( projective geometry ) ). 39. For geometry, see projective geometry . 40. Projective geometry also includes a full theory of conic sections, a subject already very well developed in Euclidean geometry.
