Hi, I have been having a tough time determining what the inner and outer radius are.

Is the only way you can determine it is by looking at a graph to see the cone or cylindrical object?

I have a graph bounded by certain regions, where it goes about the y-axis and x-axis, and some other parts of the graph.

I wanted to make sure. About the y-axis means you take the shape you have bounded by the region and then copy the same image over the y-axis (so horizontally). While about x-axis means you copy the shape below it, right?

The tough thing I have difficulty is determining what the inner and outer radius are. I tried looking through "Google," but I can only find where they just show which line matches each equation. I can see it from their diagrams when they point it out, but I have a tough time seeing it when I graph it out. Especially for inner radius and especially when I have graphs that show those "rectangles" on the line.

Like http://17calculus.com/integrals/volu...plot-large.png

Or http://17calculus.com/integrals/volu...plot-large.png

I can't really picture the shape with those rectangles.

Overall, I was wondering if someone else was able to explain it in a way I would be able to understand on finding the radius. I can do the Washer method just fine, but finding the outer and inner radius have been difficult.

Thank you.