Trigonometry
Which of the following cofunctions has the same value as sinπ9\sin\frac{\pi}{9}sin9π?
cosπ9\cos\frac{\pi}{9}cos9π
cos7π18\cos\frac{7\pi}{18}cos187π
sin7π18\sin\frac{7\pi}{18}sin187π
tan7π18\tan\frac{7\pi}{18}tan187π