LaTeX: TikZの図がいっぱいあるやつ

triangle2.tex

% pLaTeX 文書
\documentclass[dvipdfmx,a4paper]{jsarticle}% フツー
%\documentclass[dviout,a4paper]{jsarticle}% dviout!
%\usepackage{scdviout-pgf}                % 素敵!!
\usepackage{tikz}
\usetikzlibrary{calc}
\colorlet{myred}{red!80!black}
\colorlet{myblue}{blue!80!black}
\colorlet{mybrown}{yellow!20!black}
\colorlet{mygreen}{green!40!black}
\newcommand\xJp[1]{\<（#1）\<}
\newcommand\xTerm[2]{\textgt{#1}（\emph{#2}）}
\begin{document}

% 共通部分のマクロ
\newcommand\figSetCoord{%
  \coordinate (A) at (4,4);
  \coordinate (B) at (0,0);
  \coordinate (C) at (6,0);}
\newcommand\figDrawTriangle{%
  \draw[thick] (A)--(B)--(C)--cycle;
  \fill (A) circle[radius=2pt] node[above=2pt] {A};
  \fill (B) circle[radius=2pt] node[left =2pt] {B};
  \fill (C) circle[radius=2pt] node[right=2pt] {C};}

三角形の五心の中で、外心・重心・垂心の3つは特に面白い性質を満たす。

\begin{center}
  \begin{minipage}{5cm}\centering
    \xJp{1} 外心
    \begin{tikzpicture}[x=5mm,y=5mm]
      \figSetCoord
      \coordinate (O) at (3,1);
      \draw[myblue!80] (O)--($(A)!.5!(B)$);
      \draw[myblue!80] (O)--($(B)!.5!(C)$);
      \draw[myblue!80] (O)--($(C)!.5!(A)$);
      \draw[myblue!80,overlay] (O) circle[radius=3.16228];
      \fill[myblue] (O) circle[radius=2pt] node[left=2pt] {O};
      \figDrawTriangle
    \end{tikzpicture}
  \end{minipage}%
  \begin{minipage}{5cm}\centering
    \xJp{2} 重心
    \begin{tikzpicture}[x=5mm,y=5mm]
      \figSetCoord
      \coordinate (G) at (3.33333,1.33333);
      \draw[mybrown!80] (C)--($(A)!.5!(B)$);
      \draw[mybrown!80] (A)--($(B)!.5!(C)$);
      \draw[mybrown!80] (B)--($(C)!.5!(A)$);
      \fill[mybrown] (G) circle[radius=2pt] node[shift={(-4pt,6pt)}] {G};
      \figDrawTriangle
    \end{tikzpicture}
  \end{minipage}%
  \begin{minipage}{5cm}\centering
    \xJp{3} 垂心
    \begin{tikzpicture}[x=5mm,y=5mm]
      \figSetCoord
      \coordinate (H) at (4,2);
      \draw[mygreen!80] (A)--($(A)!2.0!(H)$);
      \draw[mygreen!80] (B)--($(B)!1.2!(H)$);
      \draw[mygreen!80] (C)--($(C)!1.5!(H)$);
      \fill[mygreen] (H) circle[radius=2pt] node[shift={(4pt,6pt)}] {H};
      \figDrawTriangle
    \end{tikzpicture}
  \end{minipage}
  \par\vspace{30pt}
\end{center}

任意の三角形について、外心・重心・垂心は一直線にこの順に並ぶ。
この直線のことを\xTerm{オイラー線}{Euler line}と呼ぶ。

\begin{center}
  \begin{tikzpicture}[x=10mm,y=10mm]
    \figSetCoord
    \coordinate (O) at (3,1);
    \coordinate (G) at (3.33333,1.33333);
    \coordinate (H) at (4,2);
    \draw[myblue!80] (O)--($(A)!.5!(B)$);
    \draw[myblue!80] (O)--($(B)!.5!(C)$);
    \draw[myblue!80] (O)--($(C)!.5!(A)$);
    \draw[mybrown!80] (C)--($(A)!.5!(B)$);
    \draw[mybrown!80] (A)--($(B)!.5!(C)$);
    \draw[mybrown!80] (B)--($(C)!.5!(A)$);
    \draw[mygreen!80] (A)--($(A)!2.0!(H)$);
    \draw[mygreen!80] (B)--($(B)!1.2!(H)$);
    \draw[mygreen!80] (C)--($(C)!1.5!(H)$);
    \fill[myblue] (O) circle[radius=2pt];
    \fill[mybrown] (G) circle[radius=2pt];
    \fill[mygreen] (H) circle[radius=2pt];
    \draw[myred,thick] ($(O)!-1.2!(H)$)--($(O)!2.4!(H)$);
    \node[text=myred, font=\gtfamily, below right]
      at ($(O)!2!(H)$) {オイラー線};
    \figDrawTriangle
  \end{tikzpicture}
\end{center}

\end{document}