Periodic signal
1. Period is 8.
2. X(t) is even
3. Signal not less than 0, but always less than 6
This means
1. $ \omega = \frac{2\pi}{8} $
2. This is a cosine function
3. The amplitude and offset equal 3.
$ x(t) = 3cos(\frac{2\pi}{8}t) + 3 $
