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Ch. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Briggs 3rd EditionCh. 7 - Logarithmic, Exponential Functions, and Hyperbolic Functions문제 7.3.13
7장, 문제 7.3.13

11–15. Identities Prove each identity using the definitions of the hyperbolic functions.


cosh 2x = cosh²x + sinh²x (Hint: Begin with the right side of the equation.)

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Start with the right-hand side of the equation: cosh²x + sinh²x.
Recall the definitions of the hyperbolic functions: cosh(x) = (e^x + e^(-x))/2 and sinh(x) = (e^x - e^(-x))/2.
Square both definitions: cosh²x = [(e^x + e^(-x))/2]² and sinh²x = [(e^x - e^(-x))/2]².
Expand the squares: cosh²x = (e^(2x) + 2 + e^(-2x))/4 and sinh²x = (e^(2x) - 2 + e^(-2x))/4.
Add the two results: cosh²x + sinh²x = [(e^(2x) + 2 + e^(-2x)) + (e^(2x) - 2 + e^(-2x))]/4 = (2e^(2x) + 2e^(-2x))/4 = (e^(2x) + e^(-2x))/2, which is the definition of cosh(2x).

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주요 개념

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Hyperbolic Functions

Hyperbolic functions, such as sinh(x) and cosh(x), are analogs of the trigonometric functions but are based on hyperbolas instead of circles. They are defined as sinh(x) = (e^x - e^(-x))/2 and cosh(x) = (e^x + e^(-x))/2. Understanding these definitions is crucial for manipulating and proving identities involving hyperbolic functions.
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Asymptotes of Hyperbolas

Hyperbolic Identities

Hyperbolic identities are equations that hold true for hyperbolic functions, similar to trigonometric identities. One fundamental identity is cosh²(x) - sinh²(x) = 1. Recognizing and applying these identities is essential for proving new identities, such as the one in the question.
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Asymptotes of Hyperbolas

Proof Techniques

Proof techniques in calculus often involve algebraic manipulation, substitution, and the application of known identities. In this case, starting with the right side of the equation and transforming it to match the left side using hyperbolic definitions and identities is a common strategy. Mastery of these techniques is vital for successfully proving mathematical statements.
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Initial Value Problems
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∫₁ᵉ^² dx/x√(ln²x + 1)

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