They obtained the shape of their glass by revolving this function about the x axis over the interval [-0.9,4.5]. The Maple command they used to define this function is given below.
> f := x -> if x<0 then x^4+0.088 elif x<3 then 0.088 else sin(x-3)+0.088 fi;
Plot this function (without revolving it) over the interval [-0.9,4.5] and identify the formula for each part of the graph. Then, revolve this function about the x axis over the same interval and comment on the glass Eric and Chris designed. Finally, compute the volume of the part of this glass that could be filled with liquid, assuming the stem is solid. (Hint - your integral will involve only one of the formulas used to define the function.)