\documentclass[a4paper]{book}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage[utf8]{vietnam}
\usepackage{tikz}
\usetikzlibrary{calc}
\usepackage[outline]{contour} %tạo đường viền cho chữ
\definecolor{TOP}{RGB}{0, 161, 212}
\definecolor{BLACKBLUE}{RGB}{0, 12, 49}
\definecolor{WHITEBLUE}{RGB}{0, 108, 148}
\definecolor{GRAY}{RGB}{179, 179, 179}
\definecolor{BOTTOM}{RGB}{154, 192, 45}
\pagecolor{white}
\definecolor{xanh}{RGB}{147,180,140}
\definecolor{vien}{RGB}{180,199,178}
\definecolor{leftcolor}{RGB}{33,84,51}
\definecolor{rightcolor}{RGB}{199,218,195}
\definecolor{bongcolor}{RGB}{121,121,121}
\definecolor{topgray}{RGB}{206,206,206}
\definecolor{sidegray}{RGB}{179,179,179}
\definecolor{rightgray}{RGB}{214,214,214}
\def\r{5}
\def\n{12}
\pgfmathsetmacro{\g}{180/\n}
\pgfmathsetmacro{\x}{sqrt(2)*\r*sin(\g)}
\newcommand{\hv}[1]{
\ifnum #1=0
\else
\begin{scope}
\foreach \j/\mau in {0/cyan,30/orange,60/yellow,90/violet!40!yellow,120/magenta,150/{blue!30!green},180/green,210/{red!70!green},240/pink,270/red!70!pink,300/blue,330/cyan,360/violet}{
\fill[\mau!70, draw=cyan,rotate =\j](\r,0)--++(60:\x)--++(150:\x)--++(240:\x)--cycle;
}
\end{scope}
\pgfmathtruncatemacro{\k}{#1-1}
\begin{scope}[rotate=\g,scale=1/(sqrt(2))]
\hv{\k}
\end{scope}
\fi
}
\begin{document}
\thispagestyle{empty}
\begin{tikzpicture}[remember picture, overlay]
\fill[green!10!cyan](current page.north east) rectangle([shift={(0,-4)}]current page.north west);
\fill[green!70!yellow,opacity=0.4]([shift={(0,-4)}]current page.north east)rectangle(current page.south west);
\fill[green!10!cyan]([shift={(0,3)}]current page.south east)rectangle(current page.south west)++(0,4);
\path(current page.north east)--([shift={(0,-4)}]current page.north west)node[pos=0.5]
{\bfseries\color{black}\fontfamily{pbk}\fontsize{20pt}{22pt}\selectfont Nhóm Toán và \LaTeX};
\path (current page.south west)--([shift={(0,3)}]current page.south east)node[pos=0.5,scale=2]{\textit{Tháng 8/ 2020}};
\begin{scope}
\clip ($(current page.center)+(-7,-1)$)rectangle($(current page.center)+(10,5)$);
\node at ($(current page.center)+(-6,1.3)$)[right,scale=2,shift={(1.35,0)},xslant=2,opacity=0.3]{\contour{magenta}{\bfseries\color{gray}\fontfamily{qag}\fontsize{40pt}{42pt}\selectfont MÔN TOÁN}};
\end{scope}
\begin{scope}
\clip ($(current page.center)+(-6,-1)$)rectangle($(current page.center)+(10,3)$);
\node at ($(current page.center)+(-6,1.3)$)[right,scale=2,opacity=0.8]{\contour{magenta}{\bfseries\color{orange}\fontfamily{qag}\fontsize{40pt}{42pt}\selectfont MÔN TOÁN}};
\end{scope}
\node at ($(current page.center)+(-3.7,-1.2)$)[right]{\bfseries\color{TOP}\fontfamily{qag}\fontsize{28pt}{30pt}\selectfont KỲ THI TỐT NGHIỆP THPT};
\begin{scope}[transform canvas={shift={(-3,-0.9)}}]
\node at ($(current page.center)+(3,-2)$)[right,yscale=2,xscale=1.5]{\bfseries\color{TOP}\fontfamily{qag}\fontsize{29pt}{31pt}\selectfont 20};
\contourlength{0.2mm}
\node at ($(current page.center)+(4.75,-2)$)[right,yscale=2,xscale=1.5]{
\contour{red}{\bfseries\color{white}\fontfamily{qag}\fontsize{28pt}{30pt}\selectfont 20}
};
\end{scope}
\path ([shift={(-3,-2)}]current page.north east)node[scale=0.25]{
\tikz{\hv{15}
}};
\begin{scope}[shift={(12,-21)},scale=0.7]
\def\n{5}
\def\a{1.2}
\def\b{\a/2}
\def\h{2.5*\a}
\tikzset{tru/.pic={
\fill[xanh,draw=vien](\a,\h)arc(0:360: {\a} and {\b});
\fill[left color=leftcolor,right color=rightcolor](-\a,\h)arc(180:360: {\a} and {\b})--++(-90:\h)arc(0:-180:{\a} and {\b});}}
\begin{scope}[yslant=0.5,xslant=-1.25]
\foreach \i in {1,...,\n}
\foreach \j in {1,...,\n}
{
\pgfmathparse{mod(\i+\n-\j,2) ? "topgray" : "gray!90"}
\fill[\pgfmathresult,draw=gray] (\i,\j) rectangle +(1,1);
}
\path(\n+.5,1.5)coordinate(A);
\path(5.5,4.5)node[black!75,yslant=0.5,xslant=-1.25,rotate=-90]{A}(3.5,3.5)node[black!70,yslant=0.5,xslant=-1.25,rotate=-90]{B};
\clip(0,0)--(\n,0)--(\n+1,\n+1)--(1,\n+1)--cycle;
\fill[bongcolor,opacity=0.35](4.5,1.5)--(0,4.8)--(1,10)--(3,6)--(6,2)--cycle;
\end{scope}
\begin{scope}[yslant=0.5]
\foreach \i in {1,2,...,\n}
\pgfmathparse{mod(\i,2) ? "rightgray" : "gray"}
\fill[\pgfmathresult,draw=gray]({\i-1.25},0.25)rectangle++(1,0.75);
\end{scope}
\begin{scope}[yslant=-0.3,xscale=1.25]
\foreach \i in {1,2,...,\n}
\pgfmathparse{mod(\i,2) ? "sidegray" : "gray"}
\fill[\pgfmathresult,draw=gray]({-\i+0.8},0.05)rectangle++(-1,0.75);
\end{scope}
\path (A)++(-1.5,0.2)pic{tru};
\end{scope}
\tikzset{tamgiac/.pic={
\def\a{0.75}
\def\r{1.5}
\pgfmathsetmacro{\l}{2*\r*sin(60)}
\foreach \g/\mau in {0/magenta!50,120/cyan,240/green!70}{
\begin{scope}[rotate=\g]
\path(-150:\r)coordinate(A)--(-30:\r)coordinate(B)--(90:\r)coordinate(C);
\fill[\mau](B)--(A)--([turn]60:\a)--([turn]120:{\l+3*\a})--([turn]120:{\l+4*\a})--([turn]60:\a)--([turn]120:{\l+3*\a})--cycle;
\end{scope}
}
}}
\path ([shift={(-3,-8)}]current page.center)pic{tamgiac};
\end{tikzpicture}
\end{document}
