平行四边形TikZ作图

  %!TEX program = pdflatex
 \documentclass[varwidth=true, border=2pt]{standalone}

 \usepackage{tikz}
 \usepackage{mathpazo}

 \usetikzlibrary{arrows}
 \usetikzlibrary{decorations.markings}

 \begin{document}
 \begin{tikzpicture}[x=.5cm,y=.5cm]
 \draw [<->,>=stealth'] (0,8) node [label = left:{$y$}]{} -- (0,0) -- (12,0) node[label = below:{$x$}]{};
     grid[xstep=.5cm, ystep=.5cm] (,);
     \draw (,) -- (5*1.414,0) -- (5+5*1.414,5) -- (5,5) -- cycle;
     \draw[fill=green!] (,) -- (5*1.414,0) -- (5+5*1.414,5) -- (5,5) -- cycle;
     \draw (,)node[label = below:{$(,)$}]{};
     \draw (*1.414,)node[label = below:{$(\sqrt{},)$}]{};
     \draw (+*1.414,)node[label = above:{$(\sqrt{}+,)$}]{};
     \draw (,)node[label = above:{$(,)$}]{};
   \end{tikzpicture}
 \end{document}

Parallelogram Drawing