Proof of calculating area and volume

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Discussion Overview

The discussion revolves around the formulas for calculating the area and volume of geometric shapes, specifically circles and spheres. Participants explore the origins of these formulas, the definitions of geometric terms, and the distinctions between different types of shapes. The conversation includes elements of calculus, geometry, and definitions of mathematical concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that the formulas for the perimeter and area of a circle, as well as the volume of a sphere, arise from integration.
  • One participant challenges the notion that a circle has an area, arguing that a circle is a one-dimensional object and questioning how one can speak of the area of a curve.
  • Another participant provides a visual explanation of how the area of a circle can be understood through a geometric construction involving slices of the circle.
  • There is a discussion about the definitions of geometric shapes, with some participants expressing confusion over the distinction between a circle and a disk.
  • Participants debate the terminology used to describe the area enclosed by various shapes, including triangles and polygons, and whether these shapes can be defined in terms of curves or angles.
  • One participant introduces the concept of geodesic curves in relation to triangles and angles, suggesting a more complex understanding of these definitions.

Areas of Agreement / Disagreement

Participants express differing views on whether a circle has an area, with some insisting it does not, while others refer to established terminology that includes the area of a circle. The discussion remains unresolved regarding the definitions and properties of geometric shapes.

Contextual Notes

The conversation highlights limitations in definitions and assumptions about geometric shapes, particularly regarding dimensionality and the nature of curves versus enclosed areas. There is also a lack of consensus on the terminology used to describe areas and volumes of various shapes.

Who May Find This Useful

This discussion may be of interest to individuals exploring geometric concepts, definitions in mathematics, and the relationship between calculus and geometry.

  • #31
Rogerio said:
Who is misleading people here?

According to you, if circle was just a curve, its area would be zero.

However, try google "area of a circle" and "area of a circumference", and see the difference. If it is not enough, google "area of a disk", too.

I find your arguments to be funny... :-p Sad but true... :-p

The circle is a curve.It has null area.It encloses a plain domain called DISK.

Daniel.
 
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  • #32
Rogerio said:
Who is misleading people here?

According to you, if circle was just a curve, its area would be zero.

However, try google "area of a circle" and "area of a circumference", and see the difference. If it is not enough, google "area of a disk", too.

"Circumference" is a number, not a set of points. The correct term for the set of points equi-distant from a given point is "circle" it has a circumference but its area is 0. The correct term for a the set of points bounded by a circle is "disk". It has non-zero area.

I did google on the terms you suggested. Of course, it is common to talk about the "area of a circle" when the strictly correct phrase should be "area of a disk". I notice that the hits on "area of a circumference" (there were only 4 as compared with thousands for "area of a circle" and "area of a disk") are all translations from a non-English source. I suspect that "circumference" is a mistranslation.
 

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