I used GMS package to write a maths book, and used Tikz code genrated by Geogebra to draw the image. 

The problem is there are too much white space above and below Tikz figure, as in the following picture:

![enter image description here](https://i.stack.imgur.com/RVx2N.png)

Here is the minimal working example:

```
\documentclass{gsm-l}
\usepackage[papersize={160mm,240mm},inner=20mm, outer=15mm, vmargin=15mm]{geometry}
\geometry{includeheadfoot}
\usepackage{enumitem}
\setlist[itemize]{leftmargin=*}
\usepackage{graphicx}
\DeclareGraphicsExtensions{.pdf,.png,.jpg, .tif}
\usepackage{pgf,tikz}
\usetikzlibrary{arrows}
\usepackage[utf8]{vietnam}
\begin{document}
This is the document.

\begin{definition}
 Đây là môi trường định nghĩa, và hình vẽ đi ngay sau nó.
 This is the definition environment, and the Tikz figure follows it. 
\end{definition}

 \definecolor{cqcqcq}{rgb}{0.75,0.75,0.75}
\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm,scale=0.7]
\clip(-4.3,-10.66) rectangle (17.58,6.3);
\draw (-2.3,4.08)-- (-3.74,0.04);
\draw (-3.74,0.04)-- (0.9,0.02);
\draw (0.9,0.02)-- (-2.3,4.08);
\draw (4.88,4.04)-- (3.44,0);
\draw (3.44,0)-- (8.08,-0.02);
\draw (8.08,-0.02)-- (4.88,4.04);
\begin{scriptsize}
\fill [color=black] (-2.3,4.08) circle (0.5pt);
\draw[color=black] (-2.28,4.4) node {$A$};
\fill [color=black] (-3.74,0.04) circle (0.5pt);
\draw[color=black] (-3.78,-0.18) node {$B$};
\fill [color=black] (0.9,0.02) circle (0.5pt);
\draw[color=black] (1,-0.18) node {$C$};
\draw[color=black] (-1.44,1.52) node {h.1a};
\fill [color=black] (4.88,4.04) circle (0.5pt);
\draw[color=black] (4.9,4.36) node {$A$};
\fill [color=black] (3.44,0) circle (0.5pt);
\draw[color=black] (3.4,-0.22) node {$B$};
\fill [color=black] (8.08,-0.02) circle (0.5pt);
\draw[color=black] (8.14,-0.26) node {$C=D$};
\draw[color=black] (5.74,1.48) node {h.1b};
\end{scriptsize}
\end{tikzpicture}

The above picture is left align also. 
The other question is : How can I center it? 
Please help me. 
\end{document}

```

So, how can I remove that white space? Please help me. 

Thanks.