The problem does not provide us with the fourth vertice, however, as you can see from the attached photo, we can easily infer the last vertice, since the figure is a rectangle, its opposite sides must have the same length. Hence, the last vertice is:
(1.25,-0.25)
Now that we know all the vertices, we can easily find the perimeter. As you may know, the perimeter of a rectangle is equal to the sum of all its sides:
P=2w+2h
Where:
w=width
h=height
In this case, as you can see:
w=2*(1.25)=2.5
h=2*(0.25)=0.5
Therefore, the perimeter of Central park is:
P=2*(2.5)+2(0.5)=5+1=6mi