Mệnh đề nào sau đây là sai

$ - 1 \leqslant \sin \alpha \leqslant 1;\,\, - 1 \leqslant \cos \alpha \leqslant 1$.

$\tan \alpha = \frac{{\sin \alpha }}{{\cos \alpha }}\,\,(\cos \alpha \ne 0)$.

$\tan \alpha = \frac{{\cos \alpha }}{{\sin \alpha }}\,\,(\sin \alpha \ne 0)$.

${\sin ^2}\left( {2024\alpha } \right) + {\cos ^2}\left( {2024\alpha } \right) = 2024$.