# Cavalieri's principle in 3D | Solid geometry | High school geometry | Khan Academy | Summary and Q&A

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June 22, 2020
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Cavalieri's principle in 3D | Solid geometry | High school geometry | Khan Academy

## TL;DR

Cutting and shifting shapes with the same height and cross-sectional area at any point does not change their volume.

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### Q: What is Cavalieri's principle?

Cavalieri's principle states that if two figures have the same height and cross-sectional area at any point, they have the same volume. This principle holds true for various shapes.

### Q: How does cutting and shifting shapes relate to Cavalieri's principle?

By cutting and shifting shapes with the same height and cross-sectional area, their volume remains unchanged. This demonstrates the application of Cavalieri's principle.

### Q: Can Cavalieri's principle be applied to other three-dimensional shapes?

Yes, Cavalieri's principle can be applied to different shapes such as prisms, pyramids, and spheres. As long as the height and cross-sectional area are the same at any point, the volumes will be equal.

### Q: Why is Cavalieri's principle considered intuitive?

Cavalieri's principle is intuitive because when two figures have the same cross-sectional area and height, it is easy to visualize that their volumes should be equal. Cutting and shifting the shapes does not change this intuitive understanding.

## Summary & Key Takeaways

• The video demonstrates Cavalieri's principle, which states that if two figures have the same height and cross-sectional area at any point, they have the same volume.

• Cutting and shifting shapes like cylinders, prisms, pyramids, and spheres, while maintaining the same height and cross-sectional area, does not change their original volume.

• This principle applies to various shapes and helps to develop an intuitive understanding of why equal volumes can have different shapes.