## Algebra 2 (1st Edition)

$y =-2 \cos (\dfrac{\pi}{2}) x +4$
General solution for Trigonometric functions $sine$ and $cosine$ that model a sinusoid is as follows: $y=A \sin B (x-h) +k$ and $y=A \cos B (x-h)+k$ Here, the amplitude is $A=2$ and we can see from the graph that it has flipped nature which means that we have $-2 \cos$ function. Since the time period for a trigonometric function is $4$ and here $B=\dfrac{\pi}{2}$, the midline of the graph has been shifted by $4$ vertically. Thus, we have $y =-2 \cos (\dfrac{\pi}{2}) x +4$