used standalone

tikz/dot-product-1/dot-product-1.tex

@@ -1,24 +1,18 @@
-\documentclass{article}
-\usepackage[pdftex,active,tightpage]{preview}
-\setlength\PreviewBorder{2mm}
+\documentclass[varwidth=true, border=2pt]{standalone}
 \usepackage{tikz}
 \usetikzlibrary{arrows,positioning} 
 \tikzset{
     %Define standard arrow tip
     >=stealth',
     % Define arrow style
-    pil/.style={
-           ->,
-           thick}
+    pil/.style={->,thick}
 }
 
 \begin{document}
-\begin{preview}
 \begin{tikzpicture}
     \draw[fill=green!30] (0,0) -- (90:.75cm) arc (90:27:.75cm);
     \draw[pil,color=black] (0,0) -- node[right=2pt] {$\vec a$} (27:2.2cm);
     \draw[pil,color=black] (0,0) -- node[near end, right=-3pt] {$\vec b$} (90:2cm);
     \draw(60:0.5cm) node {$\varphi$};
   \end{tikzpicture}
-\end{preview}
 \end{document}

tikz/dot-product-2/dot-product-2.tex

@@ -1,6 +1,4 @@
-\documentclass{article}
-\usepackage[pdftex,active,tightpage]{preview}
-\setlength\PreviewBorder{2mm}
+\documentclass[varwidth=true, border=2pt]{standalone}
 \usepackage{tikz}
 \usetikzlibrary{arrows,positioning} 
 \tikzset{
@@ -13,7 +11,6 @@
 }
 
 \begin{document}
-\begin{preview}
 \begin{tikzpicture}
     \draw[fill=gray!30] (27:0.90) -- node[right=-0.28cm, near end] {$\cdot$} (27:1.08)
                         arc (27:117:.18cm);
@@ -26,5 +23,4 @@
 
     \draw(60:0.35cm) node {$\varphi$};
   \end{tikzpicture}
-\end{preview}
 \end{document}

tikz/dot-product-3/Makefile

@@ -1,4 +1,4 @@
-SOURCE = dot-product-3.3
+SOURCE = dot-product-3.1
 DELAY = 80
 DENSITY = 300
 

tikz/dot-product-3/dot-product-3.1.tex

@@ -1,23 +1,17 @@
-\documentclass{article}
+\documentclass[varwidth=true, border=2pt]{standalone}
 \usepackage{gensymb}
-\usepackage[pdftex,active,tightpage]{preview}
-\setlength\PreviewBorder{2mm}
 \usepackage{tikz}
 \usetikzlibrary{arrows,positioning,decorations.pathreplacing,shapes} 
 \tikzset{
     %Define standard arrow tip
     >=stealth',
     % Define arrow style
-    pil/.style={
-           ->,
-           thick}
+    pil/.style={->,thick}
 }
 
 \begin{document}
-\begin{preview}
 \begin{tikzpicture}
     \draw[pil] (0,0)   -- node[near end, above] {$\vec a$} (3cm, 0cm);
     \draw[pil] (0,0.5cm) -- node[near end, above] {$\vec b$} (2cm,0.5cm);
   \end{tikzpicture}
-\end{preview}
 \end{document}

tikz/dot-product-6/dot-product-6.tex

@@ -1,24 +1,18 @@
-\documentclass{article}
-\usepackage[pdftex,active,tightpage]{preview}
-\setlength\PreviewBorder{2mm}
+\documentclass[varwidth=true, border=2pt]{standalone}
 \usepackage{tikz}
 \usetikzlibrary{arrows,positioning} 
 \tikzset{
     %Define standard arrow tip
     >=stealth',
     % Define arrow style
-    pil/.style={
-           ->,
-           thick}
+    pil/.style={->,thick}
 }
 
 \begin{document}
-\begin{preview}
-\begin{tikzpicture}
+  \begin{tikzpicture}
     \draw[fill=gray!30, label=$a$] (0,0) -- node[above, near start] {$\cdot$} (0.5,0)
                         arc (0:90:0.5cm);
     \draw[pil] (0,0) -- node[near end, above] {$\vec e_1$} (2cm, 0);
     \draw[pil]  (0,0) -- node[near end, right] {$\vec e_2$} (0, 2cm);
   \end{tikzpicture}
-\end{preview}
 \end{document}

tikz/equilateral-triangle-heights/equilateral-triangle-heights.tex

@@ -1,21 +1,15 @@
-\documentclass{article}
-\usepackage[pdftex,active,tightpage]{preview}
-\setlength\PreviewBorder{2mm}
+\documentclass[varwidth=true, border=2pt]{standalone}
 \usepackage{tikz}
 \usetikzlibrary{arrows,positioning, calc}
 \tikzset{
     %Define standard arrow tip
     >=stealth',
     % Define arrow style
-    pil/.style={
-           ->,
-           thick}
+    pil/.style={->,thick}
 }
 
 \begin{document}
-\begin{preview}
-\begin{tikzpicture}
-
+  \begin{tikzpicture}
     % draw the background
     \draw [line width=1.5pt, fill=gray!2] (0,0) -- (60:4) -- (4,0) -- cycle;
 
@@ -69,5 +63,4 @@
     % The triangle
     \draw [line width=1.5pt] (0,0) -- (60:4) -- (4,0) -- cycle;
   \end{tikzpicture}
-\end{preview}
 \end{document}

tikz/equilateral-triangle/equilateral-triangle.tex

@@ -1,13 +1,9 @@
-\documentclass{article}
-\usepackage[pdftex,active,tightpage]{preview}
-\setlength\PreviewBorder{2mm}
+\documentclass[varwidth=true, border=2pt]{standalone}
 \usepackage{tikz}
 \usetikzlibrary{positioning, calc}
 
 \begin{document}
-\begin{preview}
-\begin{tikzpicture}[scale=0.8]
-
+  \begin{tikzpicture}[scale=0.8]
     % draw the background
     \draw [line width=1.5pt, fill=gray!2] (0,0) -- (60:4) -- (4,0) -- cycle;
 
@@ -38,5 +34,4 @@
     % the triangle
     \draw [line width=1.5pt] (A) -- (B) -- (C) -- cycle;
   \end{tikzpicture}
-\end{preview}
 \end{document}