# Thread: Simple complex number question

1. ## Simple complex number question

Yes, both sine and cosine are periodic with period [ math]2\pi[/tex] so
1) $cos(14\pi)= cos(7(2\pi))= cos(2\pi)= cos(0)= 1$ and
2 $sin(14\pi)= sin(7(2\pi))= sin(\pi)= sin(0)= 0$.

3. I wasn't so sure about that,because in the book says they are both 0,so I posted question here just to be sure Thanks HallsofIvy!