Could someone please clarify the process for finding the volume between two curves or under one curve? I understand that the volume (V) is the integral of the cross-sectional area (A), but I am a tad confused about the different cases and what makes something a "Disk" or a "Washer". Please correct me if I am wrong about the following:
1) The forumla is $\int_{a}^{b} f(x)^2 dx$ when we are calculating the volume underneath one curve.
2) The formula is $\int_{a}^{b} (outer radius)^2 - (inner radius)^2 dx$ when calculating the volume between two curves.
Thanks!