I recently arrived to the chapter that focuses on finding volumes with integrals in the textbook I use. Integration is not the problem, but I've been having a very hard time solving these kind of exercises, (method of rings, washer method and cylindrical shell method). My complication is setting the appropriate integral and knowing what method to use. Again, the problem is not solving the integral. I'm a little bit concerned and frustrated. Please recommend a text or a book that gives a thorough explanation so that it will be very clear. Help! Thanks in advance.
PD. I use "CET" 8th Edition from J. Stewart