%!TEX root=Grafiken.tex

\usetikzlibrary{arrows}
\usetikzlibrary{snakes}

\begin{tikzpicture}[scale=1.5]

% https://tex.stackexchange.com/questions/175016/how-is-arc-defined-in-tikz

%\draw (x,y) arc (start:stop:radius); draws an arc

%with radius radius
%starts from (x,y)
%with center (x-r*cos(start), y-r*sin(start)) and
%ends at (x-r*cos(start)+r*cos(stop), y-r*sin(start)+r*sin(stop)).





    \draw[help lines] (-5,-5) grid (5,5);
  
	\draw[red] (1,0) arc (0:56:1) node[midway,xshift=-15, yshift=-6]{$\alpha$};
	
        \draw [thick,-latex] (0,0) -- (3,0);
        \draw [thick,dashed] (1,1.5) -- (4,1.5);
        \draw [thick, -latex] (0,0) -- (1,1.5);
	    \draw [thick,dashed] (3,0) -- (4,1.5);
\end{tikzpicture}
