How Is the Tan Power Series Derived Using Sin, Cos, and Bernoulli Numbers?

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Discussion Overview

The discussion centers on the derivation of the power series for the tangent function using the power series of sine and cosine, and the role of Bernoulli numbers in this context. It explores theoretical aspects of mathematical series and their relationships.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions how the tan power series can be derived from the sine and cosine power series and seeks clarification on the involvement of Bernoulli numbers.
  • Another participant suggests that deriving the tangent series from sine and cosine is generally not the standard approach, referencing an external link.
  • A third participant expresses a humorous expectation regarding the complexity of the topic and acknowledges the provided link.
  • A different participant shares a link to a resource that discusses the power series of sec x and tan x, noting that the tangent series can be derived by taking the odd terms from the expansion, while sec x corresponds to the even terms. This participant mentions that their derivation does not clarify how Bernoulli numbers are involved.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the method of deriving the tangent power series, with multiple competing views on the relevance of sine and cosine series and the role of Bernoulli numbers remaining unresolved.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the derivation methods and the specific definitions of the functions involved. The relationship between Bernoulli numbers and the tangent series is not fully explored.

Piano man
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How can the tan power series be derived from the sin and cos power series?
Where do the Bernoulli numbers come in?
 
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It's generally not done from the sine and cosine series:

http://www.mathhelpforum.com/math-help/f25/power-series-tangent-function-108861.html
 
I was expecting something yucky, and this doesn't disappoint...

Thanks for the link :)
 
Piano man. Here is a link in http://www.voofie.com/concept/Mathematics/" that you maybe interested.

http://www.voofie.com/content/117/an-explicit-formula-for-the-euler-zigzag-numbers-updown-numbers-from-power-series/"

I derived the power series of the function sec x + tan x. For the tan x power series, you just take the odd terms from the expansion, since tan x is an odd function. While sec x corresponds to the even terms from the power series, as sec x is even.

It doesn't really show how Bernoulli numbers enter the expression, but it derives an explicit form for Bernoulli numbers.
 
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