# Join two diagonal vertices of a square with an outer edge?

This is the case,I'm sorry for the drafty picture

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Welcome to tex.SX! Note that people usually don't respond to post unless you show your effort dealing with the problem, e.g. showing your source code. I made an exception because the code is trivial and you are new to the site. Hope it helps. – Ondrian Feb 24 at 19:53
OK thank you Ondrian. Now I know so next time I'll provide the code too – Jac Feb 25 at 11:11

You can use TikZ to make the picture. You can scale it to required size. See the code below.

\documentclass[border=10pt]{standalone}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}[scale=1.0]

\draw [thick] rectangle (1,1);
\draw [thick] (0,1) -- (1,0);
\draw [thick] (0,1) .. controls (1,2) and (2,1) .. (1,0);

\end{tikzpicture}
\end{document}


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Another TikZ example:

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\newcommand*{\OutAngle}{60}
\newcommand*{\ArcMax}{1.2}
\draw
(0, 0) rectangle (1, 1)
(0, 1) to[out=\OutAngle, in=135]
(\ArcMax, \ArcMax) to[out=-45, in=90-\OutAngle]
(1, 0) -- cycle
;
\end{tikzpicture}
\end{document}


The exiting angle at the top can be configured via macro \OutAngle. The maximal distance of the arc from the origin can be specified via macro \ArcMax, which is uses as x and y coordinate for the farthest point.

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Pstricks also easily yields good results:

\documentclass[border=3pt, x11names]{standalone}

\usepackage{auto-pst-pdf}

\begin{document}

\psset{unit = 2cm, dimen = m}
\begin{pspicture*}
\providecommand{\PstPolygonNode}{%
\psdots[dotstyle = o, dotsize=4pt, linecolor=LightSteelBlue3, fillstyle=solid, fillcolor=LightSteelBlue3](1;\INode)}
\PstSquare[PolyName=A]
\uput[ul](A2){A} \uput[ur](A1){B}
\uput[dr](A4){C} \uput[dl](A3){D}
\ncline[nodesep=2pt]{A2}{A4}
\pnode[0.25,0.25](A0){O}
\pstArcOAB[linecolor=LightSteelBlue3]{O}{A4}{A2}
\end{pspicture*}

\end{document}


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Thanks Bernard! – Jac Feb 25 at 11:11

Metapost provides another alternative; here I've used lualatex and luamplib but you can use plain mpost instead if you don't use lualatex yet.

I've shown four different ways to get a curve between the vertices.

\documentclass[border=5mm]{standalone}
\usepackage{luamplib}
\begin{document}
\begin{mplibcode}
beginfig(1);
u := 3cm;
path B; B = unitsquare scaled u;
draw B;
draw point 3 of B -- point 1 of B;
draw point 3 of B .. controls (u,2u) and (2u,u) .. point 1 of B withcolor .6 red;
draw point 3 of B .. controls point 2 of B      .. point 1 of B withcolor .6 blue;
draw point 3 of B {dir 60}                      .. point 1 of B withcolor .6 green;
draw point 3 of B {dir -20}                     .. point 1 of B dashed withdots;
endfig;
\end{mplibcode}
\end{document}

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