\documentclass{standalone}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetkzobj{all}
%
\usepackage{fontspec}
\setmainfont{Open Dyslexic}
%
\title{Hexagon's construction}
\begin{document}
	\begin{tikzpicture}
		\def\r{5}
		\begin{scope}
			\tkzDefPoint(0,0){O}
			\tkzDefPoint(-\r,0){A}
			\tkzDefPoint(\r,0){D}
			%
			\tkzDefCircle[radius](O,A)
			\tkzDefCircle[radius](A,O)
			\tkzDefCircle[radius](D,O)
			%
			\tkzInterCC(O,A)(A,O) \tkzGetPoints{B}{F}
			\tkzInterCC(O,A)(D,O) \tkzGetPoints{E}{C}
			%
			\tkzDefMidPoint(A,O) \tkzGetPoint{Rc}
			\tkzDefShiftPoint[Rc](0,0.2){rc}
			\node [right, align=left, color=black, font=\fontsize{12pt}{13pt}\selectfont] at (rc) {$r$};
			%
			\tkzDefMidPoint(E,D) \tkzGetPoint{Hl}
			\tkzDefShiftPoint[Hl](0.2,0.2){hl}
			\node [right, align=left, color=black, font=\fontsize{12pt}{13pt}\selectfont] at (hl) {$l \, = \, r$};
			%
			\tkzDrawCircle(O,A)
			\tkzDrawLine(A,D)
			\tkzDrawArc[delta=10](A,B)(F)
			\tkzDrawArc[delta=10](D,E)(C)
			\tkzDrawPolygon[ultra thick](A,B,C,D,E,F)
			%
			\tkzDrawPoints(O,A,D,B,F,C,E)
			\tkzLabelPoints[below left](A,O,B)
			\tkzLabelPoints[below right](D,C)
			\tkzLabelPoints[above left](F)
			\tkzLabelPoints[above right](E)
		\end{scope}
		%
	\end{tikzpicture}
\end{document}