男单 618

\usetikzlibrary{calc}
\begin{tikzpicture}
\def\L{8}
\coordinate (m) at (0.5*\L,0);
\draw (m) node[below] {$m$};
\draw[->] (0,0) -- (1.2*\L,0);
\node [circle,draw] (i) at (0,0) [minimum size=3cm] {};
\draw (i) node[below left] {$i$};
\node [circle,draw] (j) at (\L,0) [minimum size=3cm] {};
\draw (j) node[below right] {$j$};
\coordinate (a) at (tangent cs:node=i,point={(m)},solution=1);
\coordinate (c) at (tangent cs:node=i,point={(m)},solution=2);
\coordinate (b) at (tangent cs:node=j,point={(m)},solution=1);
\coordinate (d) at (tangent cs:node=j,point={(m)},solution=2);
\draw (a) node[above] {$A$} -- (i.center)-- (c) node[below] {$C$} --
(d) node[above] {$D$} -- (j.center)-- (b) node[below] {$B$} -- cycle;

\draw[dashed] (0,0) -- (0,0.5*\L);
\draw[dashed] (\L,0) -- (\L,0.5*\L);
\node (l) at (0.5*\L,0.45*\L) {$l_{ij}$};
\draw[< -] (0,0.45*\L) -- (l);
\draw[->] (l) -- (\L,0.45*\L);

\draw (m) +(0:8mm) arc (0:22:8mm);
\path (m) +(8:1.2cm) node{$\alpha_{ij}$};

\draw[dashed] (m) +($(0,0)-(a)$) -- (0,0);

\draw[->] (0,0) +(0:18mm) arc (0:-22:18mm);
\path (0,0) +(-8:22mm) node{$\alpha_{ij}$};

\draw[->] (0,0) -- (3,-2) node[below right] {$\overrightarrow{v}_{ij}$};
\draw[->] (0,0) +(0:8mm) arc (0:-32:8mm);
\path (0,0) +(-18:12mm) node{$\beta_{ij}$};

\draw[dashed] (m) +($(0,0)-(c)$) -- (0,0);
\end{tikzpicture}