Zgjidhja e ushtrimit 2

Vërteto identitetet:

1. $\sin (A + 60^{\circ}) + \sin (A - 60^{\circ}) = \sin A$
2. $\frac{\cos A}{\sin B} - \frac{\sin A}{\cos B} \equiv \frac{\cos (A + B)}{\sin B \cos B}$
3. $\frac{\sin (x + y)}{\cos x \cos y} \equiv \tan x + \tan y$
4. $\frac{\cos (x + y)}{\sin x \sin y} + 1 = \cot x \cot y$
5. $\cos\left(\theta + \frac{\pi}{3}\right) + \sqrt{3} \sin \theta = \sin\left(\theta + \frac{\pi}{6}\right)$
6. $\cot (A + B) = \frac{\cot A \cot B - 1}{\cot A + \cot B}$
7. $\sin^2 (45^{\circ} + \theta) + \sin^2 (45^{\circ} - \theta) = 1$
8. $\cos (A + B) \cos (A - B) = \cos^2 A - \sin^2 B$