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A Spinning Top

Part of the Surface Area & Volume section of Coddy's Geometry journey. Lesson 54 of 62.

A part of a solid can need its own chase before it gives a volume. A cone given by its slant height needs its height first, wherever it sits.

A cone of radius 6 and slant height 10 on a cylinder of radius 6 and height 3

This rocket is a cone on a cylinder, both of radius 6, and the cone is given by its slant height 10. Its height comes first: h^2 = 10^2 - 6^2 = 64, so h = 8. Then the cylinder holds pi × 6^2 × 3 = 108×pi and the cone 1/3 × pi × 6^2 × 8 = 96×pi. Together: 108×pi + 96×pi = 204×pi.

Plan before you tap: list what each part needs, find what is missing, then the volumes.

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Challenge

A spinning top is a cone standing on a hemisphere, both on the same circle of radius 3. The cone's slant height is 5. Find the volume of each part, then press Check.

Try it yourself

Find the marked part of the figure

Find the marked part of the figure

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This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Surface Area & Volume