۳- مقدار عددی عبارت های زیر را مشخص کنید: الف) $\sin(135^{\circ}) \times \sin(120^{\circ}) - \cos(150^{\circ}) \times \cos(135^{\circ}) =$ ب) $\tan^{2}(\frac{2\pi}{3}) - 4\tan^{2}(\frac{5\pi}{4}) + \sqrt{2}\sin(\frac{3\pi}{4}) =$ پ) $\frac{\sin(\pi - \frac{\pi}{3}) + \cos(-\frac{\pi}{4})}{\tan(-\frac{\pi}{4}) - \tan(-\frac{5\pi}{4})} =$ ت) $\frac{\cos^{2}(\frac{3\pi}{4}) - \tan^{2}(-\frac{2\pi}{3})}{\frac{\sqrt{2}}{2}\sin(-\frac{3\pi}{4}) + \frac{\sqrt{3}}{3}\cot(-\frac{5\pi}{4})} =$