Mệnh đề nào sau đây sai ?

\[ - 1 \le \sin \alpha \le 1;{\rm{ }} - 1 \le \cos \alpha \le 1.\]

\[\tan \alpha = \frac{{\sin \alpha }}{{\cos \alpha }}{\rm{ }}\left( {\cos \alpha \ne 0} \right).\]

\[\cot \alpha = \frac{{\cos \alpha }}{{\sin \alpha }}{\rm{ }}\left( {\sin \alpha \ne 0} \right).\]

\[{\sin ^2}\left( {2023\alpha } \right) + {\cos ^2}\left( {2023\alpha } \right) = 2023.\]