If \( \sin (\theta)=-\frac{1}{3} \) and \( \theta \) is in the 4th quadrant, find \( \cos (\theta) \) \( \cos (\theta)=\square \) Enter your answer as a reduced radical. Enter \( \sqrt{12} \) as \( 2 \operatorname{sqrt}(3) \).

(Uchburchakni berilgan ikki tomoni va ular orasidagi burchagi bo'yicha yechish). Agar uchburchakda \( a=6, b=4 \quad \gamma=120 \) bo'lsa, uning uchunchi tomon va qolgan burchaklarini toping.

49. Hisoblang: \( 8 \cos \frac{\pi}{7} \cdot \cos \frac{4 \pi}{7} \cdot \cos \frac{5 \pi}{7} \) A) -1 B) 4 C) 1 D) 2

7. \( \sin ^{2} A+\sin ^{2} B-\sin ^{2} C=2 \sin A \sin B \cos C \)

Solve, triangle \( A B C \) in which \( a=72.5, \angle B=60^{\circ}, \angle C=83^{\circ} \)

6. Vertetoni identitetin \( \operatorname{tg} x+\frac{1}{\operatorname{tg} x}=\frac{1}{\sin x \cdot \cos x} \)