1. Вычислить, отметив угол на окружности: a) \(sin 840°\); б) \(sin \frac{-17\pi}{4}\); в) \(sin \frac{-16\pi}{3}\); г) \(ctg \frac{7\pi}{3}\); д) \(tg \frac{-19\pi}{6}\).

1. a) \(sin 840° = sin (2 * 360° + 120°) = sin 120° = sin (180° - 60°) = sin 60° = \frac{\sqrt{3}}{2}\) б) \(sin \frac{-17\pi}{4} = -sin \frac{17\pi}{4} = -sin (4\pi + \frac{\pi}{4}) = -sin \frac{\pi}{4} = -\frac{\sqrt{2}}{2}\) в) \(sin \frac{-16\pi}{3} = -sin \frac{16\pi}{3} = -sin (5\pi + \frac{\pi}{3}) = -sin (\pi + \frac{\pi}{3}) = -(-sin \frac{\pi}{3}) = sin \frac{\pi}{3} = \frac{\sqrt{3}}{2}\) г) \(ctg \frac{7\pi}{3} = ctg (2\pi + \frac{\pi}{3}) = ctg \frac{\pi}{3} = \frac{\sqrt{3}}{3}\) д) \(tg \frac{-19\pi}{6} = -tg \frac{19\pi}{6} = -tg (3\pi + \frac{\pi}{6}) = -tg (\pi + \frac{\pi}{6}) = -tg \frac{\pi}{6} = -\frac{\sqrt{3}}{3}\)