Задание
Выполни задание
Для любого острого угла \(\alpha\) справедливы равенства \(\sin (90\degree-\alpha)=\cos \alpha\) , \(\cos (90\degree-\alpha)=\sin \alpha\) .
\(\sin (90\degree-\alpha)=\dfrac{AC}{AB}=\cos \alpha\) ,
\(\cos (90\degree-\alpha)=\dfrac{BC}{AB}=\sin \alpha\) .
| Функция | Угол \(30\degree\) | Угол \(45\degree\) | Угол \(60\degree\) |
| \(\sin\) | \(\dfrac{1}{2}\) | \(\dfrac{\sqrt{2}}{2}\) | \(\dfrac{\sqrt{3}}{2}\) |
| \(\cos\) | \(\dfrac{\sqrt{3}}{2}\) | \(\dfrac{\sqrt{2}}{2}\) | \(\dfrac{1}{2}\) |
| \(\tg\) | \(\dfrac{\sqrt{3}}{3}\) | \(1\) | \(\sqrt{3}\) |
| \(\ctg\) | \(\sqrt{3}\) | \(1\) | \(\dfrac{\sqrt{3}}{3}\) |
Вычисли значения выражений:
\(\sin 45\degree-\cos 45\degree+\tg 45\degree\) ;
\(\sin 30\degree+\cos 60\degree-1\) ;
\(\sin 60\degree\cdot \cos 30\degree+\dfrac{1}{4}\) ;
\(4\sin 30\degree\cdot \cos 60\degree-\ctg 45\degree\) ;
\(2\tg 30\degree\cdot \tg 60\degree+4{(\sin 60\degree)}^2\) ;
\(2\ctg 30\degree\cdot \ctg 60\degree+4{(\cos 30\degree)}^2\) .
Решение:
- \(\sin 45\degree-\cos 45\degree+\tg 45\degree=\dfrac{\sqrt{2}}{2}-\) _____ \(+\) _____ \(=\) _____.