[Tex/LaTex] How to do a simple TikZ picture of the golden ratio

tikz-pgf

I want to make a short article explaining the origin of the Golden Number (1+sqrt(5))/2 and I need to draw a very simple segment like the picture I've uploaded. Any suggestions?

Golden Ratio

Best Answer

Two TikZ suggestions.

enter image description here

\documentclass[tikz,border=4mm]{standalone}
\begin{document}

\begin{tikzpicture}
\pgfmathsetmacro\gratio{(1+sqrt(5))/2}
\def\lenB{2}
\path (0,0) node[coordinate](start){} ++(\gratio*\lenB,0)node[coordinate](a){} -- ++(\lenB,0)node[coordinate](b){};

\draw (start) --node[above] {$a$} (a) --node[above]{$b$} (b);

\draw [stealth-stealth] ([yshift=-9pt]start) --node[fill=white,inner ysep=0pt]{$a+b$} ([yshift=-9pt]b);

\foreach \n in {start,a,b}
  \draw (\n) ++(0,-2pt) -- ++(0,4pt);

\end{tikzpicture}
\end{document}

enter image description here

\documentclass[border=4mm,tikz]{standalone}

\usetikzlibrary{decorations.pathreplacing}

\begin{document}

\begin{tikzpicture}[decoration=brace]
\pgfmathsetmacro\gratio{(1+sqrt(5))/2}
\def\lenB{2}
\draw (0,0) node[coordinate](start){} -- ++(\gratio*\lenB,0)node[coordinate](a){} -- ++(\lenB,0)node[coordinate](b){};


\draw [decorate] ([yshift=-4pt]b) --node[below]{$a+b$} ([yshift=-4pt]start);
\draw [decorate] ([yshift=4pt]start) --node[above]{$a$} ([yshift=4pt]a);
\draw [decorate] ([yshift=4pt]a) --node[above]{$b$} ([yshift=4pt]b);

\foreach \n in {start,a,b}
  \draw (\n) ++(0,-2pt) -- ++(0,4pt);

\end{tikzpicture}
\end{document}

Code

\documentclass[tikz,convert=false]{standalone}

\begin{document}

\begin{tikzpicture}[scale=.5,auto=left,every node/.style={circle,fill=black!20}]  
        \foreach \x in {1,...,6}
        {   \node (n\x) at (\x*60:3) {\x};
        }
    \foreach \x in {1,...,5}
    {   \pgfmathtruncatemacro{\lowerbound}{\x+1}
        \foreach \y in {\lowerbound,...,6}
        {   \draw (n\x) -- (n\y);
            % for labelled edges
            %\draw (n\x) -- (n\y) node[sloped,pos=0.39,fill=white,fill opacity=0.3,above=0.1mm,rectangle, inner sep=0.1mm] {\tiny \x-\y};
        }
    }

\end{tikzpicture}

\end{document}

Output

enter image description here

Output with labels

enter image description here

Bonus homework: adapted for 36 nodes

enter image description here

[Tex/LaTex] How to draw a simple cone with height and radius with TikZ

With arc

 \documentclass[tikz,border=10pt]{standalone}
\usetikzlibrary{calc}
\begin{document}
  \begin{tikzpicture}
    \draw[dashed] (0,0) arc (170:10:2cm and 0.4cm)coordinate[pos=0] (a);
    \draw (0,0) arc (-170:-10:2cm and 0.4cm)coordinate (b);
    \draw[densely dashed] ([yshift=4cm]$(a)!0.5!(b)$) -- node[right,font=\footnotesize] {$h$}coordinate[pos=0.95] (aa)($(a)!0.5!(b)$)
                            -- node[above,font=\footnotesize] {$r$}coordinate[pos=0.1] (bb) (b);
    \draw (aa) -| (bb);
    \draw (a) -- ([yshift=4cm]$(a)!0.5!(b)$) -- (b);
  \end{tikzpicture}
\end{document}

enter image description here

With ellipse

\documentclass[tikz,border=10pt]{standalone}
\usetikzlibrary{calc}
\begin{document}
  \begin{tikzpicture}
    \begin{scope}
     \clip (-2,0) rectangle (2,1cm);
    \draw[dashed] (0,0) circle(2cm and 0.35cm);
    \end{scope}
    \begin{scope}
     \clip (-2,0) rectangle (2,-1cm);
    \draw (0,0) circle(2cm and 0.35cm);
    \end{scope}
    \draw[densely dashed] (0,4) -- node[right,font=\footnotesize] {$h$}coordinate[pos=0.95] (aa)(0,0)
                            -- node[above,font=\footnotesize] {$r$}coordinate[pos=0.1] (bb) (2,0);
    \draw (aa) -| (bb);
    \draw (-2,0) -- (0,4) -- (2,0);
  \end{tikzpicture}
\end{document}

enter image description here

Gonzalo has kindly provided the shadings to the cylinder and I am reproducing his code (with thanks):

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shadings}

\begin{document}

\begin{tikzpicture}
\fill[
  top color=gray!50,
  bottom color=gray!10,
  shading=axis,
  opacity=0.25
  ] 
  (0,0) circle (2cm and 0.5cm);
\fill[
  left color=gray!50!black,
  right color=gray!50!black,
  middle color=gray!50,
  shading=axis,
  opacity=0.25
  ] 
  (2,0) -- (0,6) -- (-2,0) arc (180:360:2cm and 0.5cm);
\draw 
  (-2,0) arc (180:360:2cm and 0.5cm) -- (0,6) -- cycle;
\draw[dashed]
  (-2,0) arc (180:0:2cm and 0.5cm);
\draw[dashed]
  (2,0) -- node[below] {$r$} (0,0) -- node[left] {h} (0,6) ;
\draw 
  (0,8pt) -- ++(8pt,0) -- (8pt,0);   
\end{tikzpicture}

\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] How to label TikZ-graphs on four vertices with a loop

Code

Output

Output with labels

Bonus homework: adapted for 36 nodes

[Tex/LaTex] How to draw a simple cone with height and radius with TikZ

Related Question