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Consider the wave shown in the image below. Which of the following wave equations describes this wave? Assume $t$ $=$ $0$.

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$y(x)=3.5\cos { (\frac { 2\pi x }{ 1.25 } ) } $

$y(x)=1.25\cos { (\frac { 2\pi x }{ 3.5 } ) } $

$y(x)=7.0\cos { (\frac { 2\pi x }{ 2.50 } ) } $

$y(x)=2.5\cos { (\frac { 2\pi x }{ 7.0 } ) } $