Curved over-head Arrows connecting Numbers

[HunterDX77M]

Hello all,

I am going to be teach my student about the FOIL method of multiplication. In order to do that, I thought it would be a nice visual helper if I could draw arrows curving from one number to another and I was wondering if that was possible with LaTeX.

For example if I have (a + b)*(c + d), I want to draw an arrow coming out of "a" going over "b" and terminating at "c". Can that be done with LaTeX?

Thanks for any input!

[cgnieder]

Very similar questions have been asked and answered on TeX.SE. Maybe one of them can give you a start:

• How to draw arrows between parts of an equation to show the Math Distributive Property (Multiplication)?
• Better solution to display the Distributive Property
• Illustrate distributive law with “broken” arrows

Regards

[localghost]

A soluton with pgf/tikZ.

Code: Select all  •  Open in writeLaTeX

\documentclass{scrartcl}
\usepackage[T1]{fontenc}
\usepackage{tikz}
\usetikzlibrary{calc,matrix}

\begin{document}
  \begin{equation}
    \begin{tikzpicture}[>=stealth,baseline,anchor=base,inner sep=0pt]
      \matrix (foil) [matrix of math nodes,nodes={minimum height=0.5em}] {
        ( & a & + & b & ) & \cdot & ( & c & + & d & ) \\
      };
      \path[->] ($(foil-1-2.north)+(0,1ex)$)   edge[red,bend left=45]    ($(foil-1-8.north)+(0,1ex)$)
                ($(foil-1-2.north)+(0,1ex)$)   edge[green,bend left=60]  ($(foil-1-10.north)+(0,0.5ex)$)
                ($(foil-1-4.north)+(0,0.5ex)$) edge[blue,bend left]      ($(foil-1-8.north)+(0,1ex)$)
                ($(foil-1-4.north)+(0,0.5ex)$) edge[orange,bend left=45] ($(foil-1-10.north)+(0,0.5ex)$);
    \end{tikzpicture}
  \end{equation}
\end{document}

Thorsten