## Why is Desargues theorem important?

Desargues’ theorem strikes us as remarkable because it identifies something common to the three points L, M and N – namely, that they lie on the same line. (Of course, any two points are collinear, but here we have three points on the same line.)

**What is Desargue geometry?**

The Desargues theorem of projective geometry states that the intersection points of two triangles ABC and a’b’c, which are the corresponding side lies on a straight line and related to each other in a visible way from one point.

### How many lines are there in Desargues geometry?

10 lines

Desargues’ Configuration has 10 points and 10 lines. Local Definitions for this geometry only! The line l is a polar of the point P if there is no line connecting P and a point on l. The point P is a pole of the line l if there is no point common to l and any line on P.

**Why is projective geometry important?**

In general, by ignoring geometric measurements such as distances and angles, projective geometry enables a clearer understanding of some more generic properties of geometric objects. Such insights have since been incorporated in many more advanced areas of mathematics.

## What kind of duality is there for the desargues theorem and its converse?

Thus, the dual of Desargues theorem is the converse of that statement, namely, “if two triangles are perspective from a line, then they are perspective from a point.” Even though the converse is the dual statement, one can not prove the converse by applying the principle of duality (as the text implies, but does not …

**What is Fano’s geometry?**

In finite geometry, the Fano plane (after Gino Fano) is the finite projective plane of order 2. It is the finite projective plane with the smallest possible number of points and lines: 7 points and 7 lines, with 3 points on every line and 3 lines through every point.

### What is four point geometry?

Four point Geometry Undefined Terms Points Lines Belongs to Axioms 1. There are exactly four distinct points 2. Any two distinct points have exactly one line 3. Each line is exactly on two points Theorems 1. If two distinct lines intersect, they contains exactly one point 2.

**Is there a concept of parallel lines in desargues geometry?**

In this new projective space (Euclidean space with added points at infinity), each straight line is given an added point at infinity, with parallel lines having a common point.

## Is projective geometry non Euclidean?

This means that it is possible to assign meanings to the terms “point” and “line” in such a way that they satisfy the first four postulates but not the parallel postulate. These are called non-Euclidean geometries. Projective geometry is not really a typical non-Euclidean geometry, but it can still be treated as such.

**What is fundamental theorem of projective geometry?**

The fundamental theorem of projective geometry states that every projective plane (sat- isfying sufficiently many axioms) is a projective plane over a commutative field, and every line-preserving bijection of such a projective plane arises through the projective action of the general linear group (possibly composed …