Why Are There Different Forms of the Integration Formula for Cosecant?

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Discussion Overview

The discussion revolves around the different forms of the integration formula for cosecant, specifically the expressions for the antiderivative of cosecant. Participants explore the validity and equivalence of these forms, including their mathematical implications and conditions.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Some participants note that the integration formula for cosecant is often presented in different forms, such as "ln |csc x - cot x| + C" and "- ln |csc x + cot x| + C".
  • One participant suggests checking the differentiation of each form to confirm they are all anti-derivatives of cosecant, indicating that they may differ only by a constant.
  • Another participant proposes a mathematical relationship where the sum of the logarithms of the two expressions equals zero, leading to the question of whether |csc^2 x - cot^2 x| equals 1.
  • A later reply asserts that since csc^2 x - cot^2 x = 1, both integration expressions are valid, noting that the difference lies in the absolute value's output affecting the sign of the result.

Areas of Agreement / Disagreement

Participants express differing views on the equivalence of the integration formulas, with some supporting the validity of both forms while others raise questions about their mathematical relationship. The discussion remains unresolved regarding the implications of the absolute values and the conditions under which each form is applicable.

Contextual Notes

Participants do not fully resolve the conditions under which the different forms of the integration formula can be used interchangeably, nor do they clarify the implications of the absolute values in the context of the integration results.

TGV320
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TL;DR
Small differences between formulas
Hi

I have a question about the integration formula of cosecant which leaves me puzzled.

I usually find it written as " = ln |csc x - cot x| + C" in most manuals, but sometimes it is written as "= - ln |csc x + cot x| + C" or "= - ln (csc x + cot x) + C".

Why is that? Can they all be used?

Thanks a lot
 
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TGV320 said:
TL;DR Summary: Small differences between formulas

Hi

I have a question about the integration formula of cosecant which leaves me puzzled.

I usually find it written as " = ln |csc x - cot x| + C" in most manuals, but sometimes it is written as "= - ln |csc x + cot x| + C" or "= - ln (csc x + cot x) + C".

Why is that? Can they all be used?

Thanks a lot
Have you tried differentiating each one to check that they are all anti-derivatives of ##cosec##? Sometimes functions that look different only differ by a constant. E.g:
$$\cos^2 x = 1 - \sin^2x$$Which means that:$$\frac d {dx} \cos^2 x = - \frac d {dx} sin^2 x$$Check that out if you want.
 
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For both expressions for the antiderivative to be correct, we must have <br /> \ln |\csc x - \cot x| + \ln |\csc x + \cot x| = \ln |\csc^2 x - \cot^2 x| = 0. So can we show that |\csc^2 x - \cot^2 x| = 1?
 
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Hi

Since cscx^2-cotx^2=1,I think it is true then, both equations do work indeed.
I have also tried to differentiate the results, and it seems that the only thing that varies is what comes out of the absolute value, therefore conditioning the positive of negative of the result.

Thanks a lot, I am grateful for your help
 

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