The Shell Method

<正>Here is another method for finding the volume of a solid of revolution.It's called the method of cylindrical shells or the shell method.For many problems,it's easier to apply than the disk method and washer method.So,what is a shell?A shell is a solid bounded by two concentric right circular cylinders(Figure 1).Some people also call it as a cylindrical shell.Shell method is always applied to a solid ob-