How Large Must a Circle Be for a Tangent to Cover an Area?

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Discussion Overview

The discussion revolves around the concept of tangents to circles and the implications of circle size on tangent interactions. Participants explore theoretical and mathematical aspects, including the nature of tangents, the geometry of circles, and the perception of flatness at different scales.

Discussion Character

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

Main Points Raised

  • One participant suggests that for a very large circle, a tangent might touch more than a single point due to the scale, using the analogy of a flat surface touching the Earth.
  • Another participant asserts that a tangent line will always touch a perfect circle at only one point, regardless of the circle's size.
  • Some participants emphasize that both the circle and the tangent line have zero width, making size irrelevant in terms of their geometric properties.
  • There is a proposal to consider how close one must be to a circle's surface for it to appear flat, raising questions about the definition of "appear flat."
  • One participant discusses the concept of a circle being identical to a line at a differential scale, while also noting that a tangent intersects curves at most once, specifically for circles.
  • Another participant challenges the idea of a circle being identical to a line, suggesting the need for clarification on the scale being referenced.
  • There is a discussion on topological perspectives, where one participant proposes that a line can be topologically equivalent to a circle, leading to further debate about the nature of lines and their endpoints.

Areas of Agreement / Disagreement

Participants express differing views on the nature of tangents and their interactions with circles, with no consensus reached on the implications of circle size or the definition of flatness. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference various scales and definitions, leading to potential ambiguities in the discussion. The relationship between tangents and curves is also explored in a mathematical context, but specific mathematical steps or definitions are not fully resolved.

prashant.d000
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Theoretically it is said that, tangent touches to a single point on a circle. But If my circle is very big, and large enough, then i think, it should not be a just single point where my tangent is touching, though is will be a very small portion depending on how large is the circle.

If i have a perfect sphere of size of earth, then a perfectly flat surface of size of football field will completely be touching on to the Earth's surface, and is not just at one point!

So, my question is, how big should be the radius of a circle, to perfectly allow 1 meter of area of a tangent touching perfectly on it?
 
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If you have a perfect circle, then a tangent line will only touch the circle at one single point. It doesn't matter how large the circle is.
 
A circle is a circle. Small or large does not matter because both the border of the circle and the tangent line are zero width.
 
Maybe another way to look at this is: how close do you need to be to the surface of the circle/sphere for it to appear flat?
 
adrianmitrea said:
Maybe another way to look at this is: how close do you need to be to the surface of the circle/sphere for it to appear flat?

Define what "appear flat" means.
 
at a small enough scale, a circle is identical to a line; i am referring to a differential scale... however, a tangent will never intersect any curve more than once.
 
adrianmitrea said:
at a small enough scale, a circle is identical to a line; i am referring to a differential scale...

A circle is never identical to a line. Or do you mean an infinitesimal scale?

however, a tangent will never intersect any curve more than once.

This is false, but it is true for a circle.
 
that is what I meant by a differential scale

also, you are right, a tangent can intersect a cubic curve in more than one point, and that is just one case...
 
from a topological point of view, both structures are infinite; without beginning or end. ie the "endpoints" of a line can coincide at infinity, and thus form a closed loop topologically equivalent to a circle. Furthermore, any segment of the line WILL contain the "center" of the line. I therefore propose that this center is the intersection of the endpoints of the line
 
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A line does not have endpoints.
 
  • #11
that is why I used quotes, they are not really points that terminate the line. they are more like the boundary of infinity; two coincident lines can "grow" at different rates, and the line that grows fastest will enclose the other line. The enclosed line would have endpoints within the outer line, as it is entirely contained in the outer line.
 

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