22.2. а) \( \cos 15^{\circ}+\cos 45^{\circ} \) б) \( \cos 46^{\circ}-\cos 74^{\circ} \)

d) \( \cos 2 x \cdot \cos x=\sin 2 x \cdot \cdot \sin x \)

If \( \tan \theta=\frac{20}{21} \), show that \( \frac{1-\sin \theta+\cos \theta}{1+\sin \theta+\cos \theta}=\frac{3}{7} \). (OR)

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

6) \( \sin x \cdot \operatorname{tg} \frac{x}{2}=0 \)

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.