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A frustum of a right circular cone with height h, lower base radius R, and top radius r.

I chose to lay it upright, revolving it wrt the y-axis.

I have coordinates B(R,0) & b(r,h), thus [tex]y=\frac{h}{r-R}(x-R) \rightarrow x=\frac{y(r-R)}{h}+R[/tex]

[tex]V=\pi\int_0^h\left[\frac{y(r-R)}{h}+R\right]^2dy[/tex]

Is my set up right? I can integrate it myself, no prob there.

Thanks!