Ecken beschriften Geometric shape

\documentclass[headheight=19pt]{scrartcl}
%------------------------------------------------------------------------------
\usepackage[ngerman]{babel}
\usepackage{amsmath}
\usepackage[norndcorners,customcolors,nofill]{hf-tikz} 
\usepackage{tikz}
\usetikzlibrary{calc}
\usetikzlibrary{shapes.geometric} % LATEX and plain TEX when using Tik Z
\usetikzlibrary[shapes.geometric] % ConTEXt when using Tik Z

%------------------------------------------------------------------------------
\tikzset{
  winkel/.style={draw=gray,angle eccentricity=.6,angle radius=0.6cm},
  mybox/.style={draw=gray,fill=white,align=left,text width=.9\linewidth}
}
\newbox\mytikzbox 
\newcommand{\tikzBox}[2][\mytikzbox]{% 
   \sbox#1{\pgfinterruptpicture#2\endpgfinterruptpicture}}

%------------------------------------------------------------------------------
\usepackage{blindtext}% für Fülltext
\begin{document}
    \begin{center}
    \begin{tikzpicture}
      \tikzBox{%
        \begin{tikzpicture}[auto]
        \tikzset{every node/.style={trapezium, draw}}
        \node[trapezium left angle=75, trapezium right angle=45]
at (0,1) {};

       \end{tikzpicture}
      }
      \node[mybox,rounded corners,font=\bfseries]
          {\parbox[t]{.6\linewidth}{%
              Dieses Beispiel funktioniert nicht. Wie vieles andere auch.
              }%
            \parbox[t]{.5\linewidth}{\centering%
            \raisebox{\dimexpr-\height+\ht\strutbox\relax}{\usebox\mytikzbox}}};
      \end{tikzpicture}
    \end{center}
\end{document}