What is the definition of the cosine function in relation to a right triangle using the adjacent side and hypotenuse?

\( \sin 20 ^ { \circ } \sin 4 \theta ^ { \circ } \sin 80 ^ { \circ } \)

Найдите множество значений функции \( y=4 \cos x-3 \) \( y \in(-1 ; 1) \)

13. а) Решите уравнение \( \sin 2 x \sin x+\sqrt{2} \cos ^{2} x=\sqrt{2} \). б) Укажите корни уравнения, принадлежащие отрезку \( \left[\frac{3 \pi}{2} ; 3 \pi\right] \)

8. Find the value of \( \sin 1485 \)

If the adjacent side measures 8 meters and the angle opposite to it is 45 degrees, calculate the length of the opposite side using trigonometric ratios.