\begin{tikzpicture}[scale=2.5]

% circles
\draw[thick] (0, 0) circle (1);
\foreach \r in {0.2, 0.4, ..., 0.8} {
	\draw[gray, dotted] (0, 0) circle (\r);
}

% lines and labels
\foreach \x in {0, 45, ..., 315} {
	\draw[gray, dotted] (0, 0) -- (\x:1);
	\draw (\x:1.15) node {$\ang{\x}$};
}

% cos circles
\draw[ultra thick, blue] (-0.5, 0) circle (0.5);
\draw[ultra thick, red] (0.5, 0) circle (0.5);
\end{tikzpicture}