Here we have a negative times a positive number. In this case The answer is always negative.
-1.15 * 3.2 = - 3.68
I think the answer is (x,y)=(3,2)
so if you notice yours
now.. normally the function
has a D value of 0, or no vertical shift, and the amplitude and the period simply make the wave taller and thinner, but the midline is still the x-axis
now, with D = 6.1, that moves the midline up vertically that much
now.. the period, well, B = 5/3, normal period of cosine is
so, the new period will be
notice the picture below
the vertical shift by the D component, or 6.1, moved the midline to y = 6.1 :)