圆、点与交点

Question

有人能向我解释一下画完圆圈后如何得到这两个点吗？

我应该如何画半圆？

Answer 1

可以使用同名库确定交集。但是，这个答案更多的是试图说服您在问题中添加最少的工作示例，即这样的文档：

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{intersections}
\begin{document}
\begin{tikzpicture}[bullet/.style={circle,fill,inner sep=1pt}]
\node[bullet,label=left:$A$] (A) at (0,0){};
\node[bullet,label=right:$B$] (B) at (7,0){};
\node[bullet,label=above:$C$] (C) at (3.5,0){};
\node[bullet,label=left:$D$] (D) at (0,-3){};
\node[bullet,label=right:$E$] (E) at (7,-3){};
\draw (A) -- (B);
\draw[name path=D--E] (D) -- (E);
\draw[name path=circle] (C) circle (3.5cm);
\path[name intersections={of=circle and D--E,by={M,H}}];
\node[bullet,label=below:$M$] at (M){};
\node[bullet,label=below:$H$] at (H){};
\end{tikzpicture}
\end{document}

还可以使用该库计算直线之间的交点calc。

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{angles,quotes,calc}
\begin{document}
\begin{tikzpicture}
 \draw[very thick] (-4,0) -- (4,0);
 \draw[very thick,line join=bevel] (0,0) coordinate(O) 
 -- (-34:4) coordinate(A) 
 -- ({-180+34}:4) coordinate(B) -- (4,0) coordinate(C);
 \draw (10:4) arc (10:-160:4);
 \path (intersection cs:first line={(O)--(A)}, second line={(B)--(C)})
 coordinate (D);
 \pic [draw,angle radius=1cm,"$\xi$"] {angle = O--D--B};
 \pic [draw,angle radius=1.5cm,"$34^\circ$"] {angle = O--A--B};
\end{tikzpicture}
\end{document}