Code:
\documentclass[tikz]{standalone}
\usetikzlibrary{intersections}
\newcounter{angle}
\setcounter{angle}{30}
\newlength\xperdeg
\setlength\xperdeg{0.166667mm}% Breite der Sinuskurve / Vollkreis (6cm/360°)
\begin{document}
\begin{tikzpicture}
\draw[black!20] (0,1.5) -- +(4.5,0) %Projektierungslinien
(0,-1.5) -- +(7.5,0)
(2,0) -- (3,0);
\draw[thick,->] (-2,0)--(2,0) node[below] {$x$};
\draw[thick,->] (0,-2)--(0,2) node[left] {$y$};
\draw[red,thick] (0,0) circle (1.5cm);
\draw (1.6,0) node[red, below]{1};
\draw (0,1.65) node[red,left]{1};
%
\draw[ultra thick,cyan] (0,0) -- (0,0 |- \theangle:1.5cm); % Siehe `texdoc pgfmanual', Abschnitt ``Intersections of Perpendicular Lines''
\draw[ultra thick,orange] (0,0) -- (\theangle:1.5cm |- 0,0);
%
\draw[densely dotted,orange] (\theangle:1.5cm) -- (\theangle:1.5cm |- 0,0);
\draw[densely dotted,cyan] (\theangle:1.5cm) -- (0,0 |- \theangle:1.5cm);
\draw[ultra thick,red,->,rotate=\theangle] (0,0) -- (1.5,0);
\draw[->] (0.5,0) arc [start angle=0, delta angle=\theangle, radius=0.5cm];
% \draw (0.75,0.25) node[anchor= south west]{$\;\varphi = \omega t + \varphi_0$};
\draw[orange] (2,2) node {\theangle$^\circ$};
\fill[black] (0,0) circle (1mm);
% \draw (1.5,-2.5) circle (0.5mm);
\draw[->] (3,-2) -- +(0,4) node[left]{$y$};
\draw[->] (3,0) -- +(6.5,0) node[below]{$t$};
\draw[blue,xshift=3cm, x=1.5cm, y=1.5cm, name path=sine curve] (0,0) sin (1,1) cos (2,0) sin (3,-1) cos (4,0);
\path[name path=proj line] (\theangle\xperdeg, -2) ++(3,0) -- +(0,4);
\draw[name intersections={of=sine curve and proj line}]
(3,0) +(\theangle\xperdeg,0) -- (intersection-1) -- (\theangle:1.5cm)
(intersection-1) circle[radius=0.5mm];
% \draw[rotate=-90,xshift=2.5cm,yshift=1.5cm] (0,0) cos++ (1.5,-1.5) sin++ (1.5,-1.5) cos++(1.5,1.5) sin++(1.5,1.5);
\end{tikzpicture}
\end{document}
0 und 360 funktioniert hier für den angle-Zähler nicht, was evtl daran liegt, daß die Sinuskurve nur berührt aber nicht geschnitten wird. Teste es erstmal mit Werten im Bereich 1..359.
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