Question

At an ocean depth of 20 meters, a buoy bobs up and then down 2 meters from the ocean's depth. Four seconds pass from the time the buoy is at its highest point to when it is at its lowest point. Assume at x = 0, the buoy is at normal ocean depth.

Use the sine tool to graph the function. The first point must be on the mid-line and the second point must be a maximum or minimum value on the graph closest to the first point.

Answer 1

y = 20 + 2 sin (2 pi t/T)
that is 0 of the sin function at t = 0
max to min is half a period t = T/2 (t = T/4 to t = 3 T/4) so T = 8 seconds
y = 20 + 2 sin ( pi t/4)
you seem to be using x for time so
y = 20 + 2 sin (pi x/4)