# Desargue\( \prime \)s Theorem

The triangles \( A_1B_1C_1 \) and \( A_2B_2C_2 \) are
*perspective with respect to a center*
if the lines \( A_1A_2 \), \( B_1B_2 \), and \( C_1C_2 \)
are concurrent. They are *perspective with respect to
an axis*
if the points \( K=B_1C_1\cap B_2C_2 \),
\( L=A_1C_1\cap A_2C_2 \), \( M=A_1B_1\cap A_2B_2 \) are colinear.

** Theorem 3 (Desargue\( \prime \)s theorem) **

Two triangles are perspective with respect to a center if
and only if they are perspective with respect to a point.