\begin{texdraw}
%\setunitscale 0.3

\drawdim in \linewd 0.015 \setunitscale 0.46
\arrowheadtype t:F
\arrowheadsize l:0.16 w:0.08

%begin textrectangle

\move(2.06 -0.02)%4
\lvec(0.53 -1.55)%2
\lvec(2.06 -1.55)%3
\lvec(2.06 -0.02)%4
\lfill f:0.8

\lvec(0.53 -0.02)%1
\lvec(0.53 -1.55)%2

\textref h:C v:C
\htext (1.29 -0.79){}
%end textrectangle

%begin textrectangle
\textref h:C v:C
\htext (0 -0.76){$R=$}
%end textrectangle
%begin textrectangle
\textref h:C v:C
\htext (1.00 -0.55){$\large \boldsymbol{0}$}
%end textrectangle
\end{texdraw}