Calculating Volume of Sphere Intersection Using Cavalieri's Principle

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Discussion Overview

The discussion revolves around calculating the volume of the intersection of two spheres, one larger than the other, with the center of the smaller sphere placed on the surface of the larger sphere. The scope includes theoretical considerations and historical methods related to geometry and volume calculation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Historical

Main Points Raised

  • One participant suggests that the problem can be approached using calculus by taking circular slices of the solid and integrating the area function over length, indicating a piecewise function based on the spheres' boundaries.
  • Another participant references a historical context, mentioning a similar problem solved by the ancient Greeks regarding the area of intersection of circles, questioning whether their methods could be extended to three dimensions for spheres.
  • A further contribution notes that Archimedes had methods to find the volume of a segment of a sphere, implying that the problem could be viewed as the sum of two such segments, and connects this to Cavalieri's principle.

Areas of Agreement / Disagreement

Participants express differing views on the methods available for solving the problem, with some advocating for calculus and others referencing historical methods. No consensus is reached on a definitive approach to the problem.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the spheres' sizes and positions, as well as the potential need for more detailed mathematical steps in the proposed solutions.

Who May Find This Useful

This discussion may be of interest to those exploring geometric problems, historical mathematics, or the application of calculus in volume calculations.

DavidSnider
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This is not homework, just a toy problem I was thinking about.

Let's say you have two spheres, one larger than the other. The center of the smaller sphere is placed on the surface of the larger sphere. How would you find the volume of the intersection?
 
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I can't think of any way to do this pre-calculus, but I can guarantee that you could do it with calculus. Take circular slices of the solid going along the radius pointing toward the center of the large sphere, find an equation for the Area of the circles based on how far you are along the radius (needs to be piecewise for which sphere you're in) and then integrate the area function over length.
 
There was a similar problem concerning area of intersection of circles which was solved by the ancient Greeks, who certainly didn't have access to calculus. Can't remember what it's called or whether the Greeks managed to extend their method to cover the 3D version of a sphere.
 
archimedes knew how to find the volume of a segment of a sphere and your problem is the sum of two such segments. his methods were essentially integral calculus, but without the antidifferentiation of the fundamental theorem.

i.e. he had what we now call cavalieri's principle and used that.
 

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