TikZ绘图示例——尺规作图:直角的画法（二）

做法

1. 作任意水平线, 并在此线上任取一点;
2. 以为圆心, 任意长为半径作圆弧;
3. 以为圆心,长为半径作圆弧, 与上一圆弧交于点, 连接并延长;
4. 以为圆心,为半径作圆弧交延长线与点;
5. 连接,即为直角.

图形

TikZ代码

\documentclass[tikz,border=3pt]{standalone}
\usetikzlibrary{calc}
\usetikzlibrary{intersections,through}

\begin{document}
    \begin{tikzpicture}[]
        % 标记两点, 做直线
        \coordinate (M) at (-.25,0);
        \coordinate (N) at (2.25,0);
        \draw [name path=AB] (M) -- (N);

        \coordinate [label=below left:$A$] (A) at (0,0);
        \coordinate [label=below right:$B$] (B) at (2,0);
        \coordinate [label=left:$C$] (C) at (0,3.464102);
        % 以A为圆心作圆弧
        \draw (B) arc (0:65:2);
        % 圆被标记为o1
        \coordinate [name path=o1,circle through=(B)] (o1) at (A);
        % 以B为圆心作圆弧
        \coordinate (O) at (1,1.732051);
        \draw (O) arc (120:115:2)
              (O) arc (120:125:2);
        % 圆被标记为o
        \coordinate [name path=o2,circle through=(A)] (o2) at (B);
        % 找交点并标记A,B
        \path [name intersections={of=o1 and o2}] 
            coordinate [label=above right:$O$] (O) at (intersection-1);
        \draw ($(B)!-.05!(O)$) -- ($(B)!2.1!(O)$);
        \draw (C) arc (120:115:2)
              (C) arc (120:125:2);
        \draw ($(C)!-.05!(A)$) -- ($(C)!1.05!(A)$);
        % 标记直角
        \draw (A) rectangle ($(A)+(.1,.1)$);
    \end{tikzpicture}
\end{document}