I am providing the code for graphing three trigonometric functions. (In the preamble, I had to put a % before the command \usetikzlibrary{calc,angles,quotes} because LaTeX could not compile it with the command. It gave me the error can't find file 'tikzlibraryangles.code.tex'. MikTeX2.9 is compiling the code.) How do I add the labels "$\scriptstyle{y = \sin(x)}," "$\scriptstyle{y = \cos(x)}," and "$\scriptstyle{y = \tan(x)}" directly under the y-axis to the corresponding graphs? Arrowheads should be at both ends of the axes. They are currently at one end. Is there a code for putting labels (in nodes) for the tick marks over other features of the graphs? How does the code instruct TikZ to marks the tick marks in half-unit increments? How do I get the code to instruct TikZ to mark the tick marks in increments of integral multiples of \pi/2? In the graphs of the tangent function, the asymptotes are solid lines. How do I get dotted lines? In the code for graphing the tangent function, there is "scaled x ticks={real:3.1415}, xtick scale label code/.code={}". What does "{real:3.1415}" and "code/.code={}" instruct TikZ to draw on the x-axis?
\documentclass{article} \usepackage{amsmath} \usepackage{tikz} %\usetikzlibrary{calc,angles,quotes} \usepackage{pgfplots} \pgfkeys{/pgfplots/Axis Style/.style={ width=13.5cm, height=5cm, axis x line=center, axis y line=middle, samples=100, ymin=-1.5, ymax=1.5, xmin=-7.0, xmax=7.0, domain=-2*pi:2*pi }} \begin{document} \begin{tikzpicture} \begin{axis}[ Axis Style, xtick={ -6.28318, -4.7123889, -3.14159, -1.5708, 1.5708, 3.14159, 4.7123889, 6.28318 }, xticklabels={ $-2\pi$, $-3\pi/2$, $-\pi$, $\pi/2$, $\pi/2$, $\pi$, $3\pi/2$, $2\pi$ } ] \addplot [mark=none, ultra thick, blue] {sin(deg(x))}; \end{axis} \end{tikzpicture} \begin{tikzpicture} \begin{axis}[ Axis Style, xtick={ -6.28318, -4.7123889, -3.14159, -1.5708, 1.5708, 3.14159, 4.7123889, 6.28318 }, xticklabels={ $-2\pi$, $-3\pi/2$, $-\pi\hspace{0.30cm}$, $\pi/2$, $\pi/2$, $\pi\hspace{0.10cm}$, $3\pi/2$, $\hspace{0.25cm} 2\pi$ } ] \addplot [mark=none, ultra thick, red] {cos(deg(x))}; \end{axis} \end{tikzpicture} \begin{tikzpicture} \begin{axis}[ Axis Style, xtick={-6.28318, -4.7123889, ..., 6.28318}, scaled x ticks={real:3.1415}, xtick scale label code/.code={}, ] \addplot [mark=none, thin, brown] {tan(deg(x))}; \end{axis} \end{tikzpicture} \end{document} 

pgfplotsmanual has answers to your questions and much, much more.