\left[\begin{array}{ccc}
\cos 180^\circ & 0 & \sin 180^\circ \\
0&1 & 0 \\
-\sin 180^\circ & 0 & \cos 180^\circ
\end{array}\right] = 
\left[\begin{array}{ccc}
-1&0&0\\
0&1&0\\
0&0&-1
\end{array}\right]