Drawing a segmented circle

Question

I'm trying to draw another larger circle that is also centered at (0,0). In words I'd like to "walk out along the top horizontal arm to its halfway point, then draw a circle all the way around to the halfway point on the bottom horizontal arm". How can I turn these words into working code?

% vacuum
\draw (15:8) arc (15:345:8);
\draw (15:8) -- ++(5,0);
\path [name path=vacuum bottom horizontal] (345:8) -- ++(6,0);
\path [name path=vacuum vertical] (15:8) -- ++(5,0) -- ++(0,-15);
\draw[name intersections={of=vacuum bottom horizontal and vacuum vertical, by=bot}]
(15:8) ++(5,0) -- (bot);
\draw (345:8) -- ++(5,0);

This is the way that I've gone about it.

% helmholtz coil
\coordinate (A) at (15:8);
\coordinate (B) at (345:8);

\draw let \p1 = ($(A) +(2.5,0)$),
\p2 = ($(B) +(2.5,0)$),
\n1 = {atan(\y1/\x1)},
\n2 = {atan(\y2/\x2)+360},
\n3 = {veclen(\x1,\y1)}
in
(\n1:\n3) arc (\n1:\n2:\n3);

MWE

Thank you all for the answers below, I plan to work through them.

score 6 · Answer 1 · answered Oct 22 '13 at 18:01

Just another solution with PSTricks.

\documentclass[pstricks,border=12pt]{standalone}
\usepackage{pst-eucl}

\begin{document}
\begin{pspicture}(-4,-4)(5,4)
    \pnodes(0,0){O}(3;15){A}([nodesep=1]A){B}(3;-15){C}([nodesep=1]C){D}
    \pstArcOAB{O}{A}{C}
    \pstArcOAB{O}{B}{D}
    \ncbar[arm=2]{A}{C}
\end{pspicture}
\end{document}

enter image description here

score 5 · Answer 2 · answered Oct 22 '13 at 16:43

You can use the package tkz-euclide for these geometric drawings:

\documentclass{article}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetkzobj{all}
\usetikzlibrary{intersections}
\begin{document}
\begin{tikzpicture}[scale=0.2]
% vacuum
\draw (15:8) arc (15:345:8);
\draw (15:8) --coordinate[pos=0.5](MPT) ++(5,0);
\path [name path=vacuum bottom horizontal] (345:8) -- ++(6,0);
\path [name path=vacuum vertical] (15:8) -- ++(5,0) -- ++(0,-15);
\draw[name intersections={of=vacuum bottom horizontal and vacuum vertical, by=bot}]
(15:8) ++(5,0) -- (bot);
\draw (345:8) --coordinate[pos=0.5](MPB) ++(5,0);
% helmholtz coil
\coordinate (A) at (15:8);
\coordinate (B) at (345:8);
\coordinate(O) at (0,0);

\tkzDrawArc[color=black](O,MPT)(MPB)
\end{tikzpicture}

\end{document}

score 5 · Answer 3 · edited Apr 13 '17 at 12:35

With the invclip key from Paul Gaborit’s answer, and the saveuse path key, you can draw this diagram relatively easy without any calculations.

Code

\documentclass[tikz]{standalone}
\tikzset{
  declare function={innerR=.8; outerR=innerR+.25; angle=15;},
  invclip/.style={
    clip,
    insert path={{[reset cm] (-16000pt,-16000pt) rectangle (16000pt,16000pt)}}},
  saveuse path/.code 2 args={
    \pgfkeysalso{#1/.estyle={insert path={#2}}}%
    \global\expandafter\let\csname pgfk@\pgfkeyscurrentpath/.@cmd\expandafter\endcsname % not optimal as it is now global through out the document
                           \csname pgfk@\pgfkeyscurrentpath/.@cmd\endcsname
    \pgfkeysalso{#1}}}
\def\invclip#1;{\pgfinterruptboundingbox\path[invclip]#1;\endpgfinterruptboundingbox}
\begin{document}
\begin{tikzpicture}
\draw [saveuse path={inner part}{(angle:innerR)
  arc[radius=innerR, start angle=angle, end angle=360-angle]
  -- ++ (right:2*outerR-2*innerR) |- (angle:innerR) -- cycle}] ;
\invclip [inner part];
\draw circle[radius=outerR];
\end{tikzpicture}
\end{document}

Output

enter image description here

Drawing a segmented circle

3 Answers3

Code

Output