Portal:Mathematics/Featured picture/2008 07

In projective geometry, Desargues' theorem, named in honor of Gérard Desargues, states:

In a projective space, two triangles are in perspective axially if and only if they are in perspective centrally.

The above picture illustrates Desargues' theorem. Another important feature of projective geometry noticeable in the picture is all lines meet at exactly one point (ie there are no parallel lines).