sin 0° = 0；sin 15° = 0.2588；sin 30° = 0.5；sin 45° = 0.7071；sin 60° = 0.8660；sin 75° = 0.9887；sin 90° = 1；sin 105° = 0.9887；sin 120° = 0.8660。0～180正余弦值表
