1. Вычислите: a) sin300°; 6) tg(-2π/3); в) 2sin(π/3) - cos(π/2).

Решение:

1. \( \sin 300^{\circ} = \sin(360^{\circ} - 60^{\circ}) = -\sin 60^{\circ} = -\frac{\sqrt{3}}{2} \).
2. \( \text{tg}\left(-\frac{2\pi}{3}\right) = -\text{tg}\left(\frac{2\pi}{3}\right) = -\text{tg}\left(\pi - \frac{\pi}{3}\right) = -(-\text{tg}\left(\frac{\pi}{3}\right)) = \text{tg}\left(\frac{\pi}{3}\right) = \sqrt{3} \).
3. \( 2\sin\left(\frac{\pi}{3}\right) - \cos\left(\frac{\pi}{2}\right) = 2 \cdot \frac{\sqrt{3}}{2} - 0 = \sqrt{3} \).

Ответ: a) \(-\frac{\sqrt{3}}{2}\); б) \(\sqrt{3}\); в) \(\sqrt{3}\).