Answer
Please see below.
Work Step by Step
Please note that the function $y=-2 \cos (2\pi x - \frac{\pi }{2} )$ has amplitude $|-2|=2$, period $\frac{2 \pi }{2 \pi }=1$, and phase shift $\frac{-\frac{\pi }{2}}{2\pi } =- \frac{1}{4}$.
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