now, with that template in mind, let's see
now the range, how far up and down it goes on the y-axis
well, for the graph of cos(x), the range is, goes up to 1, down to -1, is all,
the midline is at 0
now, with a vertical shift of 2 upwards, it moves the midline by 2 units, used to be at 0, now is at y = 2, but the amplitude never changed, is goes up and down still one unit,
but with the midline at 2, goes up to 3 and down to 1, so the range is 3 ⩽ y ⩽ 1