



 
Hi, I drew a diagram of the frustum of a cone and added some lines and labels. From the triangle $ABC$ in the diagram you can see that $\tan t = \frac{h}{Rr}.$ Solving for $R$ gives \[R = r + h \tan t.\] Substitute into the volume expression \[v= \frac{\pi}{3} \times h \times (R \times R + r \times r+ R \times r).\] This will give a quadratic in $r$. Solve for $r.$ Penny  


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