%For printing images
%\documentclass[12pt,a4paper]{amsbook}
\documentclass[border=2mm]{standalone}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{appendix}
\usepackage{cancel}
\usepackage{url}
\usepackage{bm} %bold math

\usepackage{tikz,tkz-euclide}
\usetikzlibrary{positioning}
\usetikzlibrary{patterns}
\usepackage{siunitx}
\usetkzobj{all}
\usepackage{subcaption}
%\usepackage{pgfplots}
%\usepackage{pgfmath}
%\usetikzlibrary{calc}

%For GeoGebra pictures

\usepackage{pgf,tikz,pgfplots}
\pgfplotsset{compat=1.15}
\usepackage{mathrsfs}
\usetikzlibrary{arrows}
\pagestyle{empty}

\definecolor{ududff}{rgb}{0.30196078431372547,0.30196078431372547,1.}
\definecolor{zzttqq}{rgb}{0.6,0.2,0.}
\definecolor{qqwuqq}{rgb}{0.,0.39215686274509803,0.}
\definecolor{uuuuuu}{rgb}{0.26666666666666666,0.26666666666666666,0.26666666666666666}
\definecolor{uuuuuu}{rgb}{0.26666666666666666,0.26666666666666666,0.26666666666666666}
\definecolor{xdxdff}{rgb}{0.49019607843137253,0.49019607843137253,1.}
\definecolor{ududff}{rgb}{0.30196078431372547,0.30196078431372547,1.}
\definecolor{qqqqff}{rgb}{0,0,1}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\newcommand{\R}{\mathbb{R}} % mathbb-fonts
\newcommand{\N}{\mathbb{N}}
\newcommand{\Q}{\mathbb{Q}}
\newcommand{\C}{\mathbb{C}}
\newcommand{\Chat}{{\overline{\mathbb{C}}}}
\newcommand{\Z}{\mathbb{Z}}
\newcommand{\D}{\mathbb{D}}
\renewcommand{\P}{\mathbb{P}}
\newcommand{\HH}{\mathbb{H}}%upper half plane
\def\stackrel#1#2{\mathrel{\mathop{#2}\limits^{#1}}} %stacking expressions

\DeclareMathOperator{\Real}{Re}
\DeclareMathOperator{\Imag}{Im}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{document}

\begin{tikzpicture}
\coordinate (a) at (0,0);
\coordinate (b) at ($(a)+(30:2)$);
\coordinate (c) at ($(b)+(-30:2)$);
\coordinate (d) at ($(a)+(-30:2)$);
\filldraw[color=gray!50] (a) -- (b) -- (c) -- (d) -- cycle;
%\draw (a) -- (c);
\draw (a) node[left]{$a$};
\draw (c) node[right]{$b$};
\tkzMarkAngle[size=0.7](d,a,b);
\tkzLabelAngle[pos=1](d,a,b){$\frac{\pi}{6}$};
\end{tikzpicture}

\end{document}