Преобразуй выражение и выбери верный ответ

• \(1\)
• \(- \dfrac{1}{2}\)
• \( \dfrac{1}{2}\)
• \(\dfrac{1}{\cos ^{2} \alpha}-1\)
• \(\dfrac{1}{\sin ^{2} \alpha}-1\)

\(\dfrac{\cos (\pi- \alpha) \cos (\pi +\alpha)}{\sin(\alpha -\pi)\sin (\alpha +\pi)}=\) [ ]

\(\sin (\alpha +2\pi) \sin (\pi -\alpha) - \) \(\cos (\pi +\alpha) \cos (\alpha -2\pi)=\) [ ]