What Does Cis^-1 (x) Mean and How is it Related to Cis(x)?

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SUMMARY

The term cis-1(x) refers to the inverse of the function defined as cis(x) = cos(x) + i sin(x) = eix. The discussion clarifies that cis-1(x) can be expressed as ±cos-1((x2 + 1)/(2x)). This notation is analogous to how sin-1(x) and cos-1(x) are used in trigonometry, indicating the inverse relationship of the cis function. The term "cis" stands for "cosine plus i sine," highlighting its connection to complex exponential functions.

PREREQUISITES
  • Understanding of complex numbers and Euler's formula
  • Familiarity with trigonometric functions, specifically sine and cosine
  • Knowledge of inverse trigonometric functions
  • Basic algebraic manipulation skills
NEXT STEPS
  • Study the properties of complex functions, particularly cis(x) and its applications
  • Learn about inverse trigonometric functions and their geometric interpretations
  • Explore the relationship between exponential functions and trigonometric identities
  • Investigate the implications of cis-1(x) in complex analysis
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Students of mathematics, particularly those studying complex analysis, trigonometry, and algebra. This discussion is beneficial for anyone looking to deepen their understanding of complex functions and their inverses.

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Homework Statement



What does cis^-1 (x) mean
like you know how there is sin^-1 (x) and sin(x) applying that concept with cis(x) what does that mean?

Note that is not a spelling mistake I'm not trying to say cos^-1 (x) I'm indeed saying cis^-1 (x) with an "i"

I also wander what does cis stand for like cos is cosine sin is sine etc. how do I say cis...

like I was thinking ok

cis(x) = cos(x) + i sin(x) = e^(ix)
what does cis^-1(x) mean

kind of stuck here...

Thank You

Homework Equations





The Attempt at a Solution

 
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Since cis(x) is defined in the following manner,

cis(x) = cos(x) +isin(x) = e^{ix}

Simply take the inverse of cis(x),

cis^{-1}(x) = \pm cos^{-1}(\frac{x^{2} + 1}{2x})
 
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Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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