Упрости выражения

1. \(\cos ^2 7 \beta + \sin ^2 7 \beta - \dfrac{1}{\sin ^2 2 \beta}\) ;

2. \(\tg ^2 \dfrac{\beta}{3} + \tg \dfrac{\beta}{4} \ctg \dfrac{\beta}{4}\) ;

3. \(\dfrac{1 + \ctg ^2 5 \phi (\cos ^2 5 \phi - 1)}{\sin ^2 5 \phi}\) .

Ответ: 1) [ ]; 2) [ ]; 3) [ ].