我正在尝试绘制下面的图像
到目前为止我已经完成了以下代码：
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usepackage{graphicx}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{xcolor}
\begin{document}
\begin{center}
\begin{tikzpicture}
\node at (1.5,1) {$\theta$};
\node at (5.4,0.6) {$\square$};
\node at (3.5,3.8) {$r$};
\node at (5.8,3.5) {$y$};
\node at (5.5,6) {\color{red}$(x,y)$};
\node at (5.5,5.5)[circle,red,fill,inner sep=3pt]{$ $} ;
\node[left] at (0.5,0.2) {$0$};
\node[left] at (0.5,7) {$y$};
\node[left] at (7,.2) {$x$};
\node[left] at (3,.2) {$x$};
%coordinate system
\color{black}
\draw[thick,->] (.5,0)--(.5,7);
\color{black}
\draw[thick,->] (0,.5)--(7,.5);
\color{red}
\draw{ (0.5,0.5) -- (5.5,5.5)};
\color{black}
\draw[dashed]{ (5.5,0.5) -- (5.5,5.5)};
\end{tikzpicture}
\end{center}
\end{document}
并显示：
现在，我在绘制里面的角度时遇到了困难，有人可以帮忙吗？
先感谢您。
答案1
TikZ 的原理是构建路径，您可以在其上绘制直线或曲线，并将文本放置在您想要的任何位置。
所以我把几条路径合并成一条。我注释掉了不再需要的代码。
对于角度，我使用了angles库。如果您需要更多解释，请说出来，我会更新我的答案。
\documentclass[tikz,border=5mm]{standalone}
\usetikzlibrary{angles}
%\usepackage[utf8]{inputenc}
%\usepackage{tikz}
%\usepackage{graphicx}
%\usepackage{amsmath}
%\usepackage{amssymb}
%\usepackage{xcolor}
\begin{document}
%\begin{center}
\begin{tikzpicture}
% \node at (1.5,1) {$\theta$};
% \node at (5.4,0.6) {$\square$};
% \node at (3.5,3.8) {$r$};
% \node at (5.8,3.5) {$y$};
%-------- old code -----------------
% \node at (5.5,6) {\color{red}$(x,y)$};
% \node at (5.5,5.5)[circle,red,fill,inner sep=3pt]{$ $} ;
\node (M) [circle,red,fill,inner sep=3pt,label={[red,above]:$(x,y)$}]at
(5.5,5.5){} ;
%------------------------------------
%--------- old code -----------------
%\node[left] at (0.5,0.2) {$0$};
\node (O)[below left,label=below left:$O$,inner sep=0pt] at (0,0) {};
%------------------------------------
%--------- old code ----------------
%\node[left] at (0.5,7) {$y$};
%\node[left] at (7,.2) {$x$};
%\node[left] at (3,.2) {$x$};
%coordinate system
% \color{black}
\draw[thick,->] (0,-.5)--(0,7)node[left]{$y$};
% \color{black}
\draw[thick,->] (-.5,0)--node[below]{$x$}(7,0)node[below left]{$x$};
% \color{red}
\path[draw=red] (O) -- node[above]{$r$}(M);
% \color{black}
\draw[dashed] (5.5,0)coordinate(H) -- node[right]{$y$}(M);
%-------------------------------------
\pic[draw,radius=7mm,angle eccentricity=1.5,pic text=$\theta$]{angle=H--O--M};
\pic[draw,angle radius=3mm]{right angle=M--H--O};
\end{tikzpicture}
%\end{center}
\end{document}
答案2
我稍微优化了你的代码，希望这能给你一些提示，让你知道如何更有效地使用 TikZ。你要找的角度是用 绘制的\draw (1,0) arc (0:45:1)node[midway,above right]{$\theta$};，它从 绘制一个圆弧，1,0其起始角度为0，终止角度45为 ，半径为1。它还放置了一个节点midway和above right，因此你不必在这里手动计算坐标。
\documentclass[tikz,border=5mm]{standalone}
\begin{document}
\begin{tikzpicture}
%coordinate system
\draw[thick,->] (0,-.5) -- ++(0,7)node[above left]{$y$};
\draw[thick,->] (-.5,0) -- ++(7,0)node[midway, below]{$x$} node[below right]{$x$};
\node[below left] at (0,0) {$0$};
\draw[dashed] (5,0) -- (5,5) node[midway,right]{$y$};
\draw (4.7,0) |- ++(0.3,0.3);
\draw[red] (0,0) -- (5,5) node[midway,above left,text=black]{$r$} node[circle,red,fill,inner sep=2pt]{} node[above]{$(x,y)$};
\draw (1,0) arc (0:45:1)node[midway,above right]{$\theta$};
\end{tikzpicture}
\end{document}
答案3
使用angles和quotesTikZ 库：
\documentclass[tikz,border=5mm]{standalone}
\usetikzlibrary{angles, arrows.meta,
quotes}
\begin{document}
\begin{tikzpicture}[auto,
> = Straight Barb,
dot/.style = {circle, fill, inner sep=2pt},
my angle/.style = {draw,
angle radius = 12mm,
angle eccentricity=1.2}
]
% axses
\draw[thick,->] (0,-.5) -- ++(0,7) coordinate[label=left:$y$] (y);
\draw[thick,->] (-.5,0) -- ++(7,0) coordinate[label=below:$x$] (x);
\coordinate[label=below left:$0$] (O) at (0,0);
% vector
\draw[red] (O) to [sloped, text=black, "$r$"] (45:7)
node (v) [dot, label=above:{$(x,y)$}] {};
% vector projections
\draw[densely dashed]
(v) to ["$y$"] (v |- O);
\path (O) to ["$x$" '] (v |- O) coordinate (aux);
% angles
\pic [my angle, "$\theta$"] {angle = x--O--v};
\pic [draw, angle eccentricity=.5, "$\cdot$"]
{right angle = v--aux--O};
\end{tikzpicture}
\end{document}
