Can anyone help me out on drawing the angle between the skewed lines in a 3D vector diagram? The below is my source code.
\documentclass{article}[12pt] %Use Times New Roman Font \usepackage{newtxtext,newtxmath} %\usepackage[margin=2cm]{geometry} %Plotting Package \usepackage{pgfplots} \usepackage{tikz} \usetikzlibrary{calc} \usetikzlibrary{arrows.meta,arrows} \usetikzlibrary{decorations.pathmorphing} \usetikzlibrary{decorations.markings, ext.arrows} \usepgfplotslibrary{fillbetween} \usetikzlibrary{patterns.meta,patterns} \usepackage{tkz-euclide} \pgfdeclarelayer{background} \pgfsetlayers{background,main} %Pattern fill setting \tikzdeclarepattern{ name=mylines, parameters={ \pgfkeysvalueof{/pgf/pattern keys/size}, \pgfkeysvalueof{/pgf/pattern keys/angle}, \pgfkeysvalueof{/pgf/pattern keys/line width}, }, bounding box={ (0,-0.5*\pgfkeysvalueof{/pgf/pattern keys/line width}) and (\pgfkeysvalueof{/pgf/pattern keys/size}, 0.5*\pgfkeysvalueof{/pgf/pattern keys/line width})}, tile size={(\pgfkeysvalueof{/pgf/pattern keys/size}, \pgfkeysvalueof{/pgf/pattern keys/size})}, tile transformation={rotate=\pgfkeysvalueof{/pgf/pattern keys/angle}}, defaults={ size/.initial=5pt, angle/.initial=45, line width/.initial=.4pt, }, code={ \draw [line width=\pgfkeysvalueof{/pgf/pattern keys/line width}] (0,0) -- (\pgfkeysvalueof{/pgf/pattern keys/size},0); }, } \pgfplotsset{compat=1.11} %Plot compactability \tikzstyle witharrow=[postaction={decorate,decoration={markings,mark=at position 0.5 with {\arrow[#1]{stealth}}}}] %Arrow style %\pgfplotsset{ticks=none} \pgfplotsset{tick style={black}} \usepackage[pdftex,active,tightpage]{preview} %Preview diagram as single page \begin{document} %Non-Parallel Lines and not intersected (Skewed lines) \begin{preview} \begin{tikzpicture}[x=1.5cm, y=1cm, z=-0.6cm] % Axes \draw [-stealth] (0,0,0) -- (2.8,0,0) node [xshift=0.15cm] {$x$}; \draw [-stealth] (0,0,0) -- (0,3,0) node [above,yshift=-0.1cm] {$y$}; \draw [-stealth] (0,0,0) -- (0,0,2.5) node [xshift=-0.1cm] {$z$}; % Vectors %Line 1 \draw [black!100,very thick,decoration={markings, mark=at position 0.6 with \arrow{Stealth}}, postaction=decorate] (1,2,1) -- (3.4,2,2.2); \node [xshift=0.7cm,yshift=1.2cm] at (0.7,0.65,0.1) {$\textbf{r}_1$}; %Line 2 \draw [black!100,very thick,decoration={markings, mark=at position 0.6 with \arrow{Stealth}}, postaction=decorate] (6,9,15) -- (-1,-5,-6); \node [xshift=-1cm,yshift=-1.3cm] at (1.36,0.6,0.3) {$\textbf{r}_2$}; %Origin \draw (0,0,0) node[yshift=-0.2cm] {\small{$O$}}; \end{tikzpicture} \end{preview} \end{document} Thank you.
