4. Pappus’ Theorem
If points A,B and C are on one line and
A', B' and C' are on another line then
the points of intersection of the lines
AB' and BA', AC' and CA', and BC' and
CB' lie on a common line called the
Pappus line of the configuration.
5. Pappus’
Theorem
C
B
A
A'
If points A,B and C are on one line and
A', B' and C' are on another line then
the points of intersection of the lines
AB' and BA', AC' and CA', and BC' and
CB' lie on a common line called the
Pappus line of the configuration.
B'
C'
8. Desargues’ Theorem 1
Two triangles said to be perspective
from a point if three lines joining
vertices of the triangles meet at a
corresponding common point called
the center or polar point.
9. Desargues’
Theorem 1
Two triangles said to be perspective from a point if three
lines joining vertices of the triangles meet at a
corresponding common point called the center or polar
point.
10. Desargues’ Theorem 2
Two triangles are said to be
perspective from a line if the three
points of intersection of
corresponding lines all lie on a
common line, called the axis.
11. Desargues’
Theorem 2
Two triangles are said to be perspective from a line if the
three points of intersection of corresponding lines all lie
on a common line, called the axis.
12. Desargues’ Theorem 3
Desargues' theorem states that two
triangles are perspective from a
point if and only if they are
perspective from a line.