Math 2.0

Special functions Definition

Hyperbolic cosine

Builds on Exponential function

Definition

The hyperbolic cosine is the function cosh⁡ ⁣:ℝ→ℝ\cosh \colon \mathbb{R} \to \mathbb{R} defined by cosh⁡x=ex+e−x2.\cosh x = \frac{e^x + e^{-x}}{2}.

Remarks

It is even, and cosh⁡x≥1\cosh x \ge 1, with equality only at x=0x = 0. Its power series is cosh⁡x=∑n=0∞x2n(2n)!\cosh x = \sum_{n=0}^{\infty} \frac{x^{2n}}{(2n)!}. The graph of cosh⁡\cosh is the catenary, the shape of a hanging chain. Mathlib defines it as Real.cosh.

Reading path

To understand this page from the ground up, read these 26 pages in order. The foundations come first.

Show the path as a graph
Sequence, definition, no evidence levelSequencedefinitionReal sequence, definition, no evidence levelReal sequencedefinitionBounded sequence, definition, no evidence levelBounded sequencedefinitionGeometric sequence, definition, no evidence levelGeometric sequencedefinitionLimit of a sequence, definition, no evidence levelLimit of a sequencedefinitionMonotone sequence, definition, no evidence levelMonotone sequencedefinitionSeries, definition, no evidence levelSeriesdefinitionSum of a finite geometric series, statement, no evidence levelSum of a finite geome…statementMonotone convergence theorem for sequences, statement, no evidence levelMonotone convergence …statementConvergent sequence, definition, no evidence levelConvergent sequencedefinitionSqueeze theorem, statement, no evidence levelSqueeze theoremstatementPartial sum, definition, no evidence levelPartial sumdefinitionPower series, definition, no evidence levelPower seriesdefinitionThe sequence r^n tends to zero for |r| < 1, example, no evidence levelThe sequence r^n tend…exampleRadius of convergence, definition, no evidence levelRadius of convergencedefinitionConvergent series, definition, no evidence levelConvergent seriesdefinitionA series of nonnegative terms converges iff its partial sums are bounded, statement, no evidence levelA series of nonnegati…statementAbsolute convergence, definition, no evidence levelAbsolute convergencedefinitionSum of a series, definition, no evidence levelSum of a seriesdefinitionComparison test, statement, no evidence levelComparison teststatementGeometric series, example, no evidence levelGeometric seriesexampleRatio test, statement, no evidence levelRatio teststatementRatio formula for the radius of convergence, statement, no evidence levelRatio formula for the…statementThe exponential series has infinite radius of convergence, statement, no evidence levelThe exponential serie…statementExponential function, definition, no evidence levelExponential functiondefinitionHyperbolic cosine, definition, no evidence levelHyperbolic cosinedefinition
Each page uses the pages above it. The colour of the bar on a box shows how strong the evidence is, and the box also gives it as text. The list has the same pages.
  • no evidence level
  1. Sequence definition
  2. Real sequence definition
  3. Bounded sequence definition
  4. Geometric sequence definition
  5. Limit of a sequence definition
  6. Monotone sequence definition
  7. Series definition
  8. Sum of a finite geometric series statement
  9. Monotone convergence theorem for sequences statement
  10. Convergent sequence definition
  11. Squeeze theorem statement
  12. Partial sum definition
  13. Power series definition
  14. The sequence r^n tends to zero for |r| < 1 example
  15. Radius of convergence definition
  16. Convergent series definition
  17. A series of nonnegative terms converges iff its partial sums are bounded statement
  18. Absolute convergence definition
  19. Sum of a series definition
  20. Comparison test statement
  21. Geometric series example
  22. Ratio test statement
  23. Ratio formula for the radius of convergence statement
  24. The exponential series has infinite radius of convergence statement
  25. Exponential function definition
  26. Hyperbolic cosine definition

Where this leads

6 pages build on this one.

Further reading

  1. Web https://en.wikipedia.org/wiki/Hyperbolic_functions, Exponential definitions
About this page
Tag0EQFWKJ37J
URIm2://0EQFWKJ37J
Kinddefinition
WritingW1 stated
MSC33B10
DefinesHyperbolic cosine
UsesExponential function

Markdown · JSON · Edit on GitHub

What this page needs for W2

  • edge instance_of in: one example (0 of 1)
  • edge not_instance_of in: one non-example that fails one clause (0 of 1)

The writing levels say how complete the text of a page is. They do not measure its truth.

What links here

Used by