:$$\begin{array}{l}
\begin{pmatrix}C_{n}&C_S_{n+1}\\S_C_{n+1}&S_{n+1}\end{pmatrix}\begin{pmatrix}1\\z\end{pmatrix}&=\begin{pmatrix}0&1\\-z\cdotp\bar{z}&z+\bar{z}\end{pmatrix}^n\begin{pmatrix}1\\z\end{pmatrix}\\
&=\begin{pmatrix}0&1\\-1&2\cos\theta\end{pmatrix}^n\begin{pmatrix}1\\z\end{pmatrix}
\end{array}$$