Are there multiple ways to verify a trig identity?

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Discussion Overview

The discussion revolves around the verification of trigonometric identities, exploring whether there are multiple methods to achieve this and the implications of different approaches. Participants share personal experiences, methods, and opinions regarding the verification process, touching on both theoretical and practical aspects.

Discussion Character

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

Main Points Raised

  • Some participants suggest that there are indeed multiple ways to verify trigonometric identities, depending on the starting identity.
  • Others argue that while correctness is paramount, the method of verification may vary in preference among different educators.
  • A participant shares a specific example of a trigonometric identity and outlines their steps, questioning if their approach is valid.
  • Another participant emphasizes that all proofs, if correct, are equally valid, although some may prefer more elegant solutions.
  • Concerns are raised about the clarity and method of presentation in proofs, with suggestions that starting from the left-hand side (LHS) may be more conventional.
  • Some participants recount personal experiences with disagreements over methods in academic settings, highlighting the subjective nature of teaching and verification standards.
  • There is a mention of a more complex identity that may require stricter adherence to presentation norms compared to simpler identities.
  • One participant proposes using the equivalence symbol (⇔) to clarify the steps in their proof, suggesting a way to avoid criticism.

Areas of Agreement / Disagreement

Participants express a mix of agreement and disagreement regarding the methods of verification. While some acknowledge the validity of multiple approaches, others emphasize the importance of clarity and adherence to specific methods preferred by instructors. The discussion remains unresolved on the best practices for verifying trigonometric identities.

Contextual Notes

Participants note that the simplicity of the identity in question may influence the perceived correctness of various approaches, and that more complex identities might necessitate stricter methods. There is also an acknowledgment that personal teaching experiences can shape opinions on acceptable proof methods.

  • #31
ProfuselyQuarky said:
That makes plenty of sense :smile:

When I think about, it's not that difficult to determine whether a move is legit or not.
No, it's not. If the operation you apply to both sides of an equation is one-to-one, it's reversible. For example, adding a number to or subtracting a number from each side, multiplying each side by a nonzero number, and exponentiating each side are reversible operations. In contrast, squaring both sides of an equation is not reversible.
 
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  • #32
ProfuselyQuarky said:
When I think about, it's not that difficult to determine whether a move is legit or not.

If you do these by operating on only one side - the way trig has traditionally been taught - it's automatic.
 

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