## Precalculus (6th Edition) Blitzer

Please note that a sine function $y=A\sin (Bx-C)$ has amplitude $|A|$, period $\frac{2\pi }{B}$, and phase shift $\frac{C}{B}$. So the function $y=3\sin (2x- \pi )$ has amplitude $|3|=3$, period $\frac{2\pi }{2 }=\pi$, and phase shift $\frac{\pi }{2}$.