No use of the tangent in Riemann sum?

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Discussion Overview

The discussion revolves around the role of tangents in Riemann sums and the broader relationship between integration and differentiation in calculus. Participants explore whether tangents are necessary for understanding Riemann sums and how they relate to the concepts of area and rates of change.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions the necessity of tangents in Riemann sums, emphasizing that the area under a curve is determined solely by the height and width of rectangles.
  • Another participant argues that tangents are not required for integration, noting that a function can be integrable without being differentiable.
  • A participant raises the question of whether differential calculus is entirely based on tangents and if it relates to area calculations.
  • It is suggested that the main focus of differential calculus is on determining rates (derivatives), while integration focuses on determining content (lengths, areas, volumes).
  • One participant mentions that tangents are used to find the length of a curve, prompting a follow-up question about the derivation of the arc length formula.
  • A later reply challenges the use of tangents in arc length calculations, stating that secants are typically used instead.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and role of tangents in integration and differentiation, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Some participants highlight that the relationship between integration and differentiation is complex and historically nuanced, suggesting that the discussion may depend on specific definitions and contexts.

Juwane
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Where is the use of the "tangents at every point on the curve" in the Riemann sum? Riemann sum allows us to find the area of under the curve, and this involves only the height of each rectangle (i.e. the function f(x) at each x), and the width (i.e. the x), and the two are multiplied together. This is done for every point x, and in the end all the products are added to give the final area. That's it--that's how the area under the curve is found. Where did we use the tangent in this, that they should become so important in calculus?
 
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Tangents, or the regularity conditions for their existence, are not necessary for integration (remember that a function don't need to be differentiable to be integrable, but it does to have a well-defined tangent).
The Theory of Integration may be entirely developed without mentioning derivatives (i.e. tangents), and Differentiaton may, conversely, be developed without mentioning integration.
The fact that the two are related, by the Fundamental Theorem of Calculus, is a deep fact.
 
So no tangents in integral calculus. But is differential calculus wholly based on tangents and does not have to do anything with finding areas?
 
The full answer is, of course, much more complicated, because the history behind it is complex, but the main problem of Differential Calculus is the determination of rates (that is, derivatives or tangents), where in Integration, the problem is the determination of content (lenghts, areas, volumes, etc.).
Nowadays, it the Fundamental theorem, it's usual to treat them as one subject.
 
Well, for one example of its use, tangents are used for to find the length of a curve.
 
Anonymous217 said:
Well, for one example of its use, tangents are used for to find the length of a curve.
?How? Every derivation of the formula for arclength I have seen uses secants, not tangents.
 

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