Pythagorean identity in trigonometry

E518471

The Pythagorean identity in trigonometry is a fundamental relation among sine and cosine functions, stating that for any angle θ, sin²θ + cos²θ = 1.

All labels observed (3)

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Statements (44)

Predicate Object
instanceOf trigonometric identity ⓘ
alsoKnownAs Pythagorean trigonometric identity ⓘ
fundamental trigonometric identity ⓘ
basedOn unit circle definition of sine and cosine ⓘ
category elementary trigonometry ⓘ
derivedFrom Pythagorean theorem ⓘ
domainOfθ all real numbers ⓘ
equivalentForm 1 = sin²θ + cos²θ ⓘ
cos²θ = 1 − sin²θ ⓘ
sin²θ = 1 − cos²θ ⓘ
field mathematics ⓘ
trigonometry ⓘ
generalizationOf x² + y² = 1 for points (x,y) on the unit circle ⓘ
geometricInterpretation relationship between legs and hypotenuse of a right triangle on the unit circle ⓘ
historicalOrigin rooted in ancient Greek geometry ⓘ
holdsFor all complex angles θ ⓘ
all real angles θ ⓘ
implies 0 ≤ cos²θ ≤ 1 ⓘ
0 ≤ sin²θ ≤ 1 ⓘ
nameOrigin named after the Pythagorean theorem ⓘ
prerequisiteFor Fourier analysis ⓘ
complex analysis of trigonometric functions ⓘ
signal processing ⓘ
property holds identically for all θ in its domain ⓘ
is an even function relation in θ ⓘ
relatedIdentity 1 + cot²θ = csc²θ ⓘ
1 + tan²θ = sec²θ ⓘ
statement sin²θ + cos²θ = 1 ⓘ
symmetry invariant under θ → −θ ⓘ
trueFor θ = 0 ⓘ
θ = 2π ⓘ
θ = π ⓘ
θ = π/2 ⓘ
usedFor converting between sine and cosine ⓘ
proving other trigonometric identities ⓘ
simplifying trigonometric expressions ⓘ
solving trigonometric equations ⓘ
usedIn calculus ⓘ
engineering ⓘ
geometry ⓘ
physics ⓘ
usesFunction cosine ⓘ
sine ⓘ
variable θ ⓘ

How these facts were elicited

Referenced by (3)

Full triples — surface form annotated when it differs from this entity's canonical label.

Pythagorean theorem → generalizedBy → Pythagorean identity in trigonometry ⓘ
tangent half-angle substitution → relatedTo → Pythagorean identity ⓘ
linked to: Pythagorean identity in trigonometry
Pythagorean identity in trigonometry → alsoKnownAs → Pythagorean trigonometric identity ⓘ
linked to: Pythagorean identity in trigonometry