Math CentralQuandaries & Queries


Question from Lily, a student:

A cone of height 6in. and radius of base 4in. has its top cut off by a plane parallel to its base and 4in from it.
Find the volume of the remaining frustum.

I have worked out the volume of the entire cone but I don't know how to work out the radius of the top of the frustum.


Hi Lily,

In the diagram below the triangles ABC and ADE are similar.


Write back if you need more assistance,

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