how to create a triangle with text

Question

I want create a triangle with the text inside, I'm able to the write the text but how I can create the triangle? My code for the text is

\documentclass{article}
\usepackage[english]{babel} 
\usepackage[utf8]{inputenx}
\usepackage{tkz-euclide}
\usetkzobj{all}

\begin{document}


Text1   $RT_{1,1}$ $RT_{1,2}$ $RT_{1,3}$ $RT_{1,4}$ $RT_{1,5}$................ $RT_{1,m}${\tiny \textcolor{red}{the most famous text}.\\}
Text2   $RT_{2,1}$ $RT_{2,2}$ $RT_{2,3}$ $RT_{2,4}$ ................ $RT_{2,m-1}$\\
Text3   $RT_{3,1}$ $RT_{3,2}$ $RT_{3,3}$ ................ $RT_{3,m-2}$\\
Text4   $RT_{4,1}$ $RT_{4,2}$ ................ $RT_{4,m-3}$\\
Text5   $RT_{5,1}$ ................ $RT_{5,m-4}$\\
...\\
Textj   $RT_{j,1}$ {\tiny \textcolor{red}{the less famous text}.}


\end{document}

Answer 1

I hope this is what you need...

\documentclass{article}
\usepackage{microtype,shapepar}

\def\triangleupshape{%
{0}%
{0}b{0}\\%
{8.66}t{-5}{10}\\%
{17.32}t{-10}{20}\\%
{17.32}e{0}%
}    

\begin{document}
\shapepar{\triangleupshape}A ipsum dolor sit amet, consectetuer
    adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet
 dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud
 exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo
 consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse
 molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et
 accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit
 augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet,
 consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet
 dolore magna aliquam erat volutpat. \par
\end{document}

Based on this answer, I am using the ShapePar package, it has some shapes builtin, but you can create custom ones.

There is probably a easier way to just copy the default triangular-definitions file to some directory but I just copy/paste the code.

Answer 2

Do you want something like this?

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{shadows,backgrounds}
\begin{document}
\begin{tikzpicture}
  \node (t) [align=left] {
    Text1   $RT_{1,1} RT_{1,2} RT_{1,3} RT_{1,4} RT_{1,5}$................ $RT_{1,m}$\\
      Text2   $RT_{2,1} RT_{2,2} RT_{2,3} RT_{2,4}$ ................ $RT_{2,m-1}$\\
      Text3   $RT_{3,1} RT_{3,2} RT_{3,3}$ ................ $RT_{3,m-2}$\\
      Text4   $RT_{4,1} RT_{4,2}$ ................ $RT_{4,m-3}$\\
      Text5   $RT_{5,1}$ ................ $RT_{5,m-4}$\\
      ...\\
      Textj   $RT_{j,1}$
    };
    \scoped[on background layer]{\draw [ultra thick, rounded corners=2.5mm, drop shadow, fill=white] (t.north west) -- ([xshift=10mm]t.north east) -- ([yshift=-30mm]t.south west) -- cycle ;}
\end{tikzpicture}
\end{document}

EDIT

I'm not sure whether this is the kind of placement you want or not, but it does at least show how to draw an arrow to the right of the triangle.

I made it blue for variety:

\documentclass[tikz,border=10pt]{standalone}
\usetikzlibrary{shadows,backgrounds,positioning,arrows.meta}
\begin{document}
\tikzset{
  my blue/.style={
    text=black,
    ultra thick,
    draw=blue!50!cyan,
  }
}
\begin{tikzpicture}[my blue]
  \node (t) [align=left] {
    Text1   $RT_{1,1} RT_{1,2} RT_{1,3} RT_{1,4} RT_{1,5}$................ $RT_{1,m}$\\
    Text2   $RT_{2,1} RT_{2,2} RT_{2,3} RT_{2,4}$ ................ $RT_{2,m-1}$\\
    Text3   $RT_{3,1} RT_{3,2} RT_{3,3}$ ................ $RT_{3,m-2}$\\
    Text4   $RT_{4,1} RT_{4,2}$ ................ $RT_{4,m-3}$\\
    Text5   $RT_{5,1}$ ................ $RT_{5,m-4}$
  };
  \node (r) [below=25pt of t.south west, anchor=north west] {\dots};
  \node (s) [below=25pt of r.south west, anchor=north west] {Textj   $RT_{j,1}$};
  \scoped[on background layer]{\draw [rounded corners=7.5pt, drop shadow, inner color=blue!50!cyan!10, outer color=blue!50!cyan!20, my blue] (t.north west) -- ([xshift=25pt]t.north east) coordinate (p) -- ([yshift=-40pt]s.south west) coordinate (q) -- cycle ;}
  \draw [my blue, -{Stealth[]}] ([xshift=10pt] q -| p) -- ([xshift=10pt]p);
\end{tikzpicture}
\end{document}

To answer your follow-up concerning the addition of text, the easiest way is to add the node on the path which draws the arrow. For example, rather than

   \draw [my blue, -{Stealth[]}] ([xshift=10pt] q -| p) -- ([xshift=10pt]p);

you could say

  \draw [my blue, -{Stealth[]}] ([xshift=10pt] q -| p) -- ([xshift=10pt]p) node [right, midway, align=left] {Testo allineato\\a destra} node [above left, at end, align=right] {top\\node} node [at start, below, align=center] {bottom\\node} node [pos=.25, right, align=left] {yet\\another\\node} node [above right, align=left] {another\\node};

to produce

I'm not quite sure how many nodes you want or precisely where, so I've provided a selection to demonstrate various possibilities which you can modify according to need.