The amplitude is 5. The negative sign in front of it just means that it goes down to -5 first instead of up to +5 like it would if it wasn't negative. Anyway, the period of it is [tex] \frac{2 \pi }{3} [/tex], and the phase shift is [tex] \frac{ \pi }{3} [/tex]. The midline is the vertical shift, which is 2.
