Like any other function, when we add or subtract a number at the end of the equation, it will either move the equation up (if it's positive) or move it down (if it's negative). We have a +3, so the parent cos function moves up 3. It oscillates between y values of 4 and 2 and 3 is its midline. So, in summary, the new function looks exactly like the parent, same size and shape and orientation, it's just shifted up 3 units.