%%
%% The LaTeX Companion, 3ed
%%
%% Example 6-7-10 on page I-481 in "diagbox --- Making table cells with diagonal lines".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.0pt}

%StartShownPreambleCommands
\usepackage{tabularx,diagbox}
%StopShownPreambleCommands

\begin{document}
\begin{tabularx}{\textwidth}{|p{1cm}|X|X|}  \hline
 \diagbox[innerwidth=1cm]{A}{B} &
 \diagbox[dir=SW,innerwidth=\hsize]{AA}{BB} &
 \diagbox[innerwidth=\hsize]{AAA}{BBB} \\ \hline
\end{tabularx}
\end{document}