I've just created an SVG version with TikZ and Inkscape from an old PNG version of an image on wikipedia. This is how they look like:
You might notice, that the text of the left image is much easier to read. One reason is the color, but the othr is defitely the font.
How can I make the text easier to read?
I thick making the text (all formulae) bold would be a good start. If this isn't enough, it might be necessary to change from the italic font to a normal one.
The current source is on github. Here is the source that was used for the image above:
\documentclass[varwidth=true, border=2pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes, calc, shapes, arrows}
\usepackage{amsmath,amssymb}
\usepackage{xcolor}
\definecolor{xvectorcolor}{HTML}{77933C}
\begin{document}
\begin{tikzpicture}[]
% Punkte
\coordinate (A) at (0,0) {};
\coordinate (B) at (5,0) {};
\coordinate (C) at (2,2) {};
% Draw the triangle
\path[fill=blue!10, fill=blue!10] (A) -- (B) -- (C) -- (A);
\draw[->, ultra thick,fill=gray!10, xvectorcolor, arrows={-latex}] (A) -- (C) node[sloped,midway,above] {$x$};
\draw[->, ultra thick,fill=gray!10, blue!80, arrows={-latex}] (C) -- (B) node[sloped,midway,above] {$y$};
\draw[->, ultra thick,fill=gray!10, red!80, arrows={-latex}] (A) -- (B) node[sloped,midway,above] {$z = x + y$};
\coordinate (A) -- (B) node[sloped,midway,below] {$\|z\| = \|x+y\| \leq \|x\| + \|y\|$};
\end{tikzpicture}
\end{document}
font=\boldmath
to thetikzpicture
options to make the math bold.\mathsf{...}
provided the best result so far.mathptmx
ortxfonts
.