Create similar triangles symbol

Question

In my country, the similar triangle symbol is different to \cong or \sim symbol. I draw the symbol with TikZ package so it is not compatible with sizes and color. Please help me create the symbol with TeX command. Thank you very much.

P.S The code draws similar symbol.

\documentclass[tikz,border=2mm]{standalone}
\begin{document}
\begin{tikzpicture}[baseline=-7pt,scale=0.1,line width=0.65pt]
\draw (-2,0);
\draw (4,0);
\draw (0,0) arc (90:270:1)..controls +(0:1) and +(180:1).. (2,0) arc (90:-90:1);
\end{tikzpicture}
\end{document}

The curve is no doubt aesthetic-- with minimal and complete arcs and curves connected smoothly. However, I'm a bit curious to know (nothing related to LaTeX, though) in which country a pair of similar triangles are denoted by a symbol having nothing to do with straight lines even ! — Partha D., May 21 '21 at 06:41
@ParthaD. I’m guessing, rotated S for sembables? (Without going into that history.) — Davislor, May 21 '21 at 19:41
@Davislor Yes, that's a good catch at linguistic etymology. Similar and semblance all start with S, whose colloquial form could be \sim (how come I never wondered before !) and more puritan form the rotated "S". Nice ! — Partha D., May 22 '21 at 06:48

score 6 · Answer 1 · answered May 21 '21 at 01:40

6

∽ (U+223D) is \backsim in the packages unicode-math, stix or stix2.

You could instead put a sans-serif S inside a \rotatebox from graphicx.

You can also put a tikzpicture inside \mathrel and use it as a relation symbol in math mode.

answered May 21 '21 at 01:40

Davislor

44,045

1

Thank you very much for your help! The second option is useful! https://ibb.co/fxRGhxL – Nam Tran Le May 21 '21 at 02:26

Juan Castaño · Accepted Answer · 2021-05-21T18:19:14.700

6

If you like your tikz symbol there is another simple option. You can wrap it inside a macro and use scalable units. Something like this:

\documentclass{article}
\usepackage   {tikz}
\newcommand{\similar}
{%
  \mathrel%
  {%
    \begin{tikzpicture}[baseline=(a.south),line width=0.15ex]
      \node (a) {};
      \draw (0,0.5ex) arc (90:270:0.5ex) .. controls +(0:0.5ex) and +(180:0.5ex) .. (1ex,0.5ex) arc (90:-90:0.5ex);
    \end{tikzpicture}
  }
}
\begin{document}
The red triangles {\color{red} $ABC \similar DEF$} are similar.
So are the big triangles {\large $A'B'C' \similar  D'E'F'$}.
\end{document}

Edit: As Davislor suggested I wrapped all in a \mathrel for a better spacing.

edited May 21 '21 at 18:19

answered May 21 '21 at 10:20

Juan Castaño

28,426

Thank you very much! – Nam Tran Le May 21 '21 at 11:03
It is equal to the original. +1 – Sebastiano May 21 '21 at 11:22
1

@Sebastiano, thanks!!. Yes it's the same, I only changed the units and wrapped it inside a macro. – Juan Castaño May 21 '21 at 11:24
The technique is scalable ex unit. It is not equal to the original code. Juan Castaño's code is quite good! – Nam Tran Le May 21 '21 at 11:27
Like I mentioned at the end of my answer, you want to wrap it in \mathrel for correct spacing. – Davislor May 21 '21 at 15:49
@Davislor, you are right. I made an edit and added the \mathrel. It looks better :-) – Juan Castaño May 21 '21 at 18:20

Create similar triangles symbol

2 Answers2