我希望原点是 $D=E=F=A=(0,0)$，而不是 $D$。此图代码如下：
\begin{tikzpicture}[extended line/.style={shorten >=-#1,shorten <=-#1}, extended line/.default=1cm]
\pgfmathsetmacro\d{0}
\pgfmathsetmacro\b{2}
\pgfmathsetmacro\f{4}
\pgfmathsetmacro\m{0.4}
\pgfmathsetmacro\q{3}
\pgfmathsetmacro\a{-1}
%\pgfmathsetmacro\b{0}
\pgfmathsetmacro\c{5}
%named
%\coordinate[label=above:$A$](A)at(\a,0);
\coordinate[label=above:$B$](B)at(\b,\m*\b+\q-1.76);
\coordinate[label=above:$C$](C)at(\c,\m*\c+\q);
\coordinate[label=below:$D$](D)at(\d,0);
%\coordinate[label=below:$E$](E)at(\e,0);
%\coordinate[label=below:$F$](F)at(\f,0);
\draw [extended line=0.5cm] (D)--(C);
% coordinates system
\draw[red, ->] (\d-1,0)--(\d+5,0);
\draw[red, ->] (0,-1)--(0,\d+5);
\fill (B)circle(2pt) (C)circle(2pt) (D)circle(2pt);%
%\fill[blue] (P)circle(2pt) (Q)circle(2pt) (R)circle(2pt);
\end{tikzpicture}
答案1
代替
\coordinate[label=below:$D$](D)at(\d,0);
写
\coordinate[label=below:{$D=E=F=A=(0,0)$}](D)at(\d,0);
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