<u>Answer:</u>
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<u>Step-by-step explanation:</u>
From the graph, we can see that y = -1 when x = 0.
So to check whether which of the given options is the equation of the given graph, we will set our calculator to the radian mode and then plug the value of x as 0.
1. y = cos(x + pi/2) = cos(0 + pi/2) = 0
2. y = cos(x+2pi) = cos(0+2pi) = 1
3. y = cos(x+pi/3) = cos(0+pi/3) = 1/2 = 0.5
4. y = cos(x+pi) = cos(0+pi) = -1
Therefore, the equation of this graph is y = cos(x+pi) = cos(0+pi) = -1.