Nguyễn Minh Hà
Abstract
First, I will introduce the basic definitions of two concepts: projective plane and extended complex plane. Then, I prove that the concept of cross ratio in the extended complex plane is the extension of cross ratio in the projective plane. Finally, I discuss the meaning of two concepts: the projective plane, and the extended complex plane.
Κάντε κλικ στην εικόνα.
Introduction
First, without using the coordinate system nor the projection that turns the sphere into a plane, I will introduce the following concepts in a rudimentary way: the projective plane and the extended complex plane. Then, I prove that the concept of cross ratio in the extended complex plane is the extension of cross ratio in the projective plane.
Finally, using Pappus theorem and Fuerbach theorem, I will talk about the meaning of two concepts: the projective plane and the extended complex plane.
For easy to follow, please note that: the normal plane is called the real plane; the ordinary plane on which a complex coordinate system is attached is called the complex plane.
