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Trigonometric Properties and Identities Cheat Sheet by

Trigonometry Cheat Sheet for definitions, properties, and identities of Circular & Hyperbolic functions and their inverses. θ, φ, x, and y are all real numbers, with θ and φ in radians. z is a complex variable of the form a+bi, where a and b are real numbers, and i is the imaginary unit. C=Circular, H=Hyperbolic, I=-Inverse

Circular Functions Defini­tions

Name
Right-­Tri­angle Definition
Domain
Range
Sine Function
sin(θ)=o/h
(-∞,∞)
[-1,1]
Cosine Function
cos(θ)=a/h
(-∞,∞)
[-1,1]
Tangent Function
tan(θ)=o/a
{θ|θ≠π­/2±πn}
(-∞,∞)
Cosecant Function
csc(θ)=h/o
{θ|θ≠±πn}
(-∞,-1­]∪[1,∞)
Secant Function
sec(θ)=h/a
{θ|θ≠π­/2±πn}
(-∞,-1­]∪[1,∞)
Cotangent Function
cot(θ)=a/o
{θ|θ≠±πn}
(-∞,∞)
Inverse Sine Function
arcsin­(o/h)=θ
[-1,1]
[-π/2,π/2]
Inverse Cosine Function
arccos­(a/h)=θ
[-1,1]
[0,π]
Inverse Tangent Function
arctan­(o/a)=θ
(-∞,∞)
(-1,1)
Inverse Cosecant Function
arccsc­(h/o)=θ
(-∞,-1­)∪(1,∞)
[-π/2,­0)∪­(0,π/2]
Inverse Secant Function
arcsec­(h/a)=θ
(-∞,-1­)∪(1,∞)
[0,π/2­)∪(­π/2,π]
Inverse Cotangent Function
arccot­(a/o)=θ
(-∞,∞)
(0,1)
Circular Euler Relation
e±iθ=cos(θ­)±i­sin(θ)
De Moivre's Theorem
einθ=(cos(­θ)+­isi­n(θ))n=cos(n­θ)+­isi­n(nθ)
n ∈ ℕ1 = {1,2,3­­­­­,­4­­,­­­5­­­,...}
"­h" is the "­hyp­ote­nus­e" leg of a right triangle. It is directly across the right (90°) angle, and it has the longest length of the three sides.
"­o" is the "­opp­osi­te" leg of a right triangle. It is directly across the chosen angle θ.
"­a" is the "­adj­ace­nt" leg of a right triangle. It is the leg that is neither the hypotenuse leg, nor the opposite leg.
By the Pythag­orean theorem, o2+a2=h2

Hyperbolic Functions Defini­tions

Name
Expone­ntial Definition
Domain
Range
Hyperbolic Sine Function
sinh(θ)=(eθ-e)/2
(-∞,∞)
(-∞,∞)
Hyperbolic Cosine Function
cosh(θ)=(eθ+e)/2
(-∞,∞)
[1,∞)
Hyperbolic Tangent Function
tanh(θ)=(eθ-e)/(eθ+e)
(-∞,∞)
(-1,1)
Hyperbolic Cosecant Function
csch(θ­)=2/(eθ-e)
(-∞,0)­∪(0,∞)
(-∞,0)­∪(0,∞)
Hyperbolic Secant Function
sech(θ­)=2/(eθ+e)
(-∞,∞)
(0,1]
Hyperbolic Cotangent Function
coth(θ)=(eθ+e)/(eθ-e)
(-∞,0)­∪(0,∞)
(-∞,-1­)∪(1,∞)
Inverse Hyperbolic Sine Function
arcsin­h(x­)=ln(x+(x2+1))
(-∞,∞)
(-∞,∞)
Inverse Hyperbolic Cosine Function
arccos­h(x­)=ln(x+(x2-1))
[1,∞)
[0,∞)
Inverse Hyperbolic Tangent Function
arctan­h(x­)=½­ln(­(1+­x)/­(1-x))
(-1,1)
(-∞,∞)
Inverse Hyperbolic Cosecant Function
arccsc­h(x­)=l­n((1±(1+x2))/x)
(-∞,0)­∪(0,∞)
(-∞,0)­∪(0,∞)
Inverse Hyperbolic Secant Function
arcsec­h(x­)=l­n((1+(1-x2))/θ)
(0,1]
[0,∞)
Inverse Hyperbolic Cotangent Function
arccot­h(x­)=½­ln(­(x+­1)/­(x-1))
(-∞,-1­)­∪­(1,∞)
(-∞,0)­­∪(0,∞)
Hyperbolic Euler Relation
e±θ=cosh(­θ)±­sinh(θ)
De Moivre's Theorem (Hyper­bolic)
e=(cosh­(θ)­+si­nh(θ))n=cosh(­nθ)­+si­nh(nθ))
n ∈ ℕ1 = {1,2,3­­­­­,­4­­,­­­5­­­,...}

Complex Defini­tions

Name
Complex Relation
Circul­ar-­Hyp­erbolic Relation
Complex Sine
sin(z)=(eiz-e-iz)/2i
sin(z)­=-i­sin­h(iz)
Complex Cosine
cos(z)=(eiz+e-iz)/2
cos(z)­=co­sh(iz)
Complex Tangent
tan(z)­=-i(eiz-e-iz)/(eiz+e-iz)
tan(z)­=-i­tan­h(iz)
Complex Cosecant
csc(z)­=2i/(eiz-e-iz)
csc(z)­=ic­sch(iz)
Complex Secant
sec(z)­=2/(eiz+e-iz)
sec(z)­=se­ch(iz)
Complex Cotangent
cot(z)=i(eiz+e-iz)/(eiz-e-iz)
cot(z)­=ic­oth(iz)
Complex Inverse Sine
arcsin­(z)­=-i­ln(iz±(1-z2))
arcsin­(z)­=-i­arc­sin­h(iz)
Complex Inverse Cosine
arccos­(z)­=-i­ln(z±i(1-z2))
arccos­(z)­=±i­arc­cosh(z)
Complex Inverse Tangent
arctan­(z)­=(i­/2)­ln(­(i+­z)/­(i-z))
arctan­(z)­=-i­arc­tan­h(iz)
Complex Inverse Cosecant
arccsc­(z)­=-i­ln((i+(z2-1))/z)
arccsc­(z)­=ia­rcc­sch(iz)
Complex Inverse Secant
arcsec­(z)­=-i­ln((1+(1-z2))/z)
arcsec­(z)­=±i­arc­sech(z)
Complex Inverse Cotangent
arccot­(z)­=-(­i/2­)ln­((z­+i)­/(z-i))
arccot­(z)­=±i­arc­cot­h(iz)
Complex Hyperbolic Sine
None
sinh(z­)=-­isi­n(iz)
Complex Hyperbolic Cosine
None
cosh(z­)=c­os(iz)
Complex Hyperbolic Tangent
None
tanh(z­)=-­ita­n(iz)
Complex Hyperbolic Cosecant
None
csch(z­)=i­csc(iz)
Complex Hyperbolic Secant
None
sech(z­)=s­ec(iz)
Complex Hyperbolic Cotangent
None
coth(z­)=i­cot(iz)
Complex Inverse Hyperbolic Sine
None
arcsin­h(z­)=-­iar­csi­n(iz)
Complex Inverse Hyperbolic Cosine
None
arccos­h(z­)=±­iar­ccos(z)
Complex Inverse Hyperbolic Tangent
None
arctan­h(z­)=-­iar­cta­n(iz)
Complex Inverse Hyperbolic Cosecant
None
arccsc­h(z­)=-­iar­ccs­c(iz)
Complex Inverse Hyperbolic Secant
None
arcsec­h(z­)=±­iar­csec(z)
Complex Inverse Hyperbolic Cotangent
None
arccot­h(z­)=-­iar­cco­t(iz)
i=(-1)
z is a complex variable of the form a+bi, where a and b are real numbers, and i is the imaginary unit

Circular Functions Unit Circle Values

θ (Radians)
θ (Degrees)
sin(θ)
cos(θ)
tan(θ)
csc(θ)
sec(θ)
cot(θ)
0
0
1
0
undefined
1
undefined
π/6
30°
1/2
3/2
3/3
2
23/3
3
π/4
45°
2/2
2/2
1
2
2
1
π/3
60°
3/2
1/2
3
23/3
2
3/3
π/2
90°
1
0
undefined
1
undefined
0
 
2π/3
120°
3/2
-1/2
-3
23/3
-2
-3/3
3π/4
135°
2/2
-2/2
-1
2
-2
-1
5π/6
150°
1/2
-3/2
-3/3
2
-23/3
-3
π
180°
0
-1
0
undefined
-1
undefined
 
7π/6
210°
-1/2
-3/2
3/3
-2
-23/3
3
5π/4
225°
-2/2
-2/2
1
-2
-2
1
4π/3
240°
-3/2
-1/2
3
-23/3
-2
3/3
3π/2
270°
-1
0
undefined
-1
undefined
0
 
5π/3
300°
-3/2
1/2
-3
-23/3
2
-3/3
7π/4
315°
-2/2
2/2
-1
-2
2
-1
11π/6
330°
-1/2
3/2
-3/3
-2
23/3
-3
360°
0
1
0
undefined
1
undefined
The coordi­nates (cos(θ), sin(θ)) represent x and y coordi­nates of θ on the unit circle x2+y2=1

Circular Compos­itional Identities

Compos­ition
sin(x)
cos(x)
tan(x)
arcsin(x)
x
(1-x2)
x/(1-x2)
arccos(x)
(1-x2)
x
(1-x2)/x
arctan(x)
x/(1+x2)
1/(1+x2)
x
arccsc(x)
1/x
(x2-1)/|x|
±1/(x2-1)
arcsec(x)
(x2-1)/|x|
1/x
±(x2-1)
arccot(x)
1/(1+x2)
x/(1+x2)
1/x
Each compos­ition is valid on different domains

Hyperbolic Compos­itional Identities

Compos­ition
sinh(x)
cosh(x)
tanh(x)
arcsinh(x)
x
(1+x2)
x/(1-x2)
arccosh(x)
(x2-1)
x
(x2-1)/x
arctanh(x)
x/(1-x2)
1/(1-x2)
x
arccsch(x)
1/x
(x2+1)/|x|
1/(x2+1)
arcsech(x)
(1-x2)/x
1/x
(1-x2)
arccoth(x)
x/(1-x2)
|x|/(x2-1)
1/x
Each compos­­ition is valid on different domains

Circular Quotient & Reciprocal Identities

Tangent Quotient
tan(θ)­=si­n(θ­)/c­os(θ)
Cotangent Quotient
cot(θ)­=co­s(θ­)/s­in(θ)
 
Sine Reciprocal
sin(θ)­=1/­csc(θ)
Cosine Reciprocal
cos(θ)­=1/­sec(θ)
Tangent Reciprocal
tan(θ)­=1/­cot(θ)
Cosecant Reciprocal
csc(θ)­=1/­sin(θ)
Secant Reciprocal
sec(θ)­=1/­cos(θ)
Cotangent Reciprocal
cot(θ)­=1/­tan(θ)
All the following identities are true for values that do not cause division by zero

Cofunc­tional Phase Shift Properties

Sine Compli­mentary
sin(θ)­=co­s(π­/2-θ)
Sine Supple­mentary
sin(θ)­=si­n(π-θ)
Cosine Compli­mentary
cos(θ)­=si­n(π­/2-θ)
Cosine Supple­mentary
cos(θ)­=-c­os(π-θ)
Tangent Compli­mentary
tan(θ)­=co­t(π­/2-θ)
Tangent Supple­mentary
tan(θ)­=-t­an(­πn-θ)
Cosecant Compli­mentary
csc(θ)­=se­c(π­/2-θ)
Cosecant Supple­mentary
csc(θ)­=cs­c(π-θ)
Secant Compli­mentary
sec(θ)­=cs­c(π­/2-θ)
Secant Supple­mentary
sec(θ)­=-s­ec(π-θ)
Cotangent Compli­mentary
cot(θ)­=ta­n(π­/2-θ)
Cotangent Supple­mentary
cot(θ)­=-c­ot(­πn-θ)
n ∈ ℕ1 = {1,2,3­­­­­,­4­­,­­­5­­­,...}

Period­icity Properties

Sine Period­icity
sin(θ)­=si­n(θ­±2πn)
Cosine Period­icity
cos(θ)­=co­s(θ­±2πn)
Tangent Period­icity
tan(θ)­=ta­n(θ±πn)
Cosecant Period­icity
csc(θ)­=cs­c(θ­±2πn)
Secant Period­icity
sec(θ)­=se­c(θ­±2πn)
Cotangent Period­icity
cot(θ)­=co­t(θ±πn)
n ∈ ℕ1 = {1,2,3­­­­­,­4­­,­­­5­­­,...}

Circular Parity Properties

Sine Odd
sin(-θ­)=-­sin(θ)
Cosine Even
cos(-θ­)=c­os(θ)
Tangent Odd
tan(-θ­)=-­tan(θ)
Cosecant Odd
csc(-θ­)=-­csc(θ)
Secant Even
sec(-θ­)=s­ec(θ)
Cotangent Odd
cot(-θ­)=-­cot(θ)

Circular Pythag­orean Identities

Sine-C­osine Pythag­orean
sin2(θ)+cos2(θ)=1
Secant­-Ta­ngent Pythag­orean
tan2(θ)+1=sec2(θ)
Coseca­nt-­Cot­angent Pythag­orean
1+cot2(θ)=csc2(θ)
The last two Pythag­orean Identities are obtained by dividing all the terms of the original Sine-C­osine Identity by cos²(θ) and sin²(θ), respec­tively

(C) Half/M­ult­ipl­e-Angle Identities

Sine Half-Angle
sin(θ/2)=±(½(1-c­os(θ)))
Cosine Half-Angle
cos(θ/2)=±(½(1+c­os(θ)))
Tangent Half-Angle 1
tan(θ/2)=±((1-co­s(θ­))/­(1+­cos­(θ)))
Tangent Half-Angle 2
tan(θ/­2)=­(1-­cos­(θ)­)/s­in(θ)
Tangent Half-Angle 3
tan(θ/­2)=­sin­(θ)­/(1­+co­s(θ))
 
Sine Double­-Angle 1
sin(2θ­)=2­sin­(θ)­cos(θ)
Sine Double­-Angle 2
sin(2θ­)=2­tan­(θ)­/(1+tan2(θ))
Cosine Double­-Angle 1
cos(2θ­)=cos2(θ)-sin2(θ)
Cosine Double­-Angle 2
cos(2θ­)=2cos2(θ)-1
Cosine Double­-Angle 3
cos(2θ­)=1­-2sin2(θ)
Cosine Double­-Angle 4
cos(2θ­)=(­1-tan2(θ))/(­1+tan2(θ))
Tangent Double­-Angle 1
tan(2θ­)=2­tan­(θ)­/(1-tan2(θ))
Tangent Double­-Angle 2
tan(2θ­)=2­/(c­ot(­θ)-­tan(θ))
 
Sine Triple­-Angle
sin(3θ­)=3­sin­(θ)­-4sin3(θ)
Cosine Triple­-Angle
cos(3θ­)=4cos3(θ)-3c­os(θ)
Tangent Triple­-Angle
tan(3θ­)=(­3ta­n(θ­)-tan3(θ))/(­1-3tan2(θ))
Sine Multip­le-­Angle Formula: sin(nθ)=∑nk=0 (nk)cosk(θ)sinn-k(θ)sin­((π­/2)­(n-k))
Cosine Multip­le-­Angle Formula: cos(nθ)=∑nk=0 (nk)cosk(θ)sinn-k(θ)cos­((π­/2)­(n-k))
All the following identities are true for values that do not cause division by zero

Circular Sum/Di­ffe­ren­ce/­Product Identities

Sine Sum/Di­ffe­rence
sin(θ±φ)
­sin­(­θ)­­cos­(φ)­±co­s(θ­)­s­in(φ)
Sine Sum-Pr­oduct
sin(θ)­±sin(φ)
2sin((­θ±φ­)/2­)co­s((­θ∓φ)/2)
Sine Produc­t-Sum
sin(θ)­sin(φ)
½(cos(­θ-φ­)-c­os(­θ+φ))
Cosine Sum/Di­ffe­rence
cos(θ±φ)
­cos­(­θ)­­cos­(φ)­∓si­n(θ­)­s­in(φ)
Cosine Sum-Pr­oduct
cos(θ)­±cos(φ)
2cos((­θ±φ­)/2­)co­s((­θ∓φ)/2)
Cosine Produc­t-Sum
cos(θ)­cos(φ)
½(cos(­θ-φ­)+c­os(­θ+φ))
Sine-C­osine Produc­t-Sum
sin(θ)­cos(φ)
½(sin(­θ-φ­)+s­in(­θ+φ))
Tangent Sum/Di­ffe­rence
tan(θ±φ)
(tan(θ­)±t­an(­φ))­/(1­∓ta­n(θ­)ta­n(φ))
Tangent Sum
tan(θ)­±tan(φ)
sin(θ±­φ)/­(co­s(θ­)co­s(φ))
Tangent Product
tan(θ)­tan(φ)
(tan(θ­)+t­an(­φ))­/(c­ot(­θ)+­cot(φ))
Tangen­t-C­ota­ngent Product
tan(θ)­cot(φ)
(tan(θ­)+c­ot(­φ))­/(c­ot(­θ)+­tan(φ))

Sine and Cosine Unit Circle

x2+y2=1
 

Circul­ar-­Inverse Reciprocal Identities

Sine Reciprocal
arcsin­(1/­x)=­arc­csc(x)
Cosine Reciprocal
arccos­(1/­x)=­arc­sec(x)
Tangent Reciprocal 1
arctan­(1/­x)=­arc­cot(x), x>0
Tangent Reciprocal 2
arctan­(1/­x)=­arc­cot­(x)-π, x<0
Cosecant Reciprocal
arccsc­(1/­x)=­arc­sin(x)
Secant Reciprocal
arcsec­(1/­x)=­arc­cos(x)
Cotangent Reciprocal 1
arccot­(1/­x)=­arc­tan(x), x>0
Cotangent Reciprocal 2
arccot­(1/­x)=­arc­tan­(x)+π, x<0

Circul­ar-­Inverse Compli­mentary Identities

Sine Compli­mentary
arcsin­(x)­=π/­2-a­rcc­os(x)
Cosine Compli­mentary
arccos­(x)­=π/­2-a­rcs­in(x)
Tangent Compli­mentary
arctan­(x)­=π/­2-a­rcc­ot(x)
Cosecant Compli­mentary
arccsc­(x)­=π/­2-a­rcs­ec(x)
Secant Compli­mentary
arcsec­(x)­=π/­2-a­rcc­sc(x)
Cotangent Compli­mentary
arccot­(x)­=π/­2-a­rct­an(x)

Circul­ar-­Inverse Negative Input Identities

Sine Odd
arcsin­(-x­)=-­arc­sin(x)
Cosine Transl­ation
arccos­(-x­)=π­-ar­ccos(x)
Tangent Odd
arctan­(-x­)=-­arc­tan(x)
Cosecant Odd
arccsc­(-x­)=-­arc­csc(x)
Secant Transl­ation
arcsec­(-x­)=π­-ar­csec(x)
Cotangent Transl­ation
arccot­(-x­)=π­-ar­ccot(x)

(CI) Half/M­ultiple Substi­tution Identities

Half Sine Substi­tution 1
½arcsi­n(x­)=a­rcsin((1+x)/­2))-π/4
Half Sine Substi­tution 2
½arcsi­n(x­)=π­/4-­arcsin((1-x)/2))
Half Cosine Substi­tution 1
½arcco­s(x­)=a­rccos(((1+x)/2))
Half Cosine Substi­tution 2
½arcco­s(x­)=π­/2-­arccos((1-x)/2))
 
Double Sine Substi­tution
2arcsi­n(x­)=a­rcs­in(2x(1-x2)), |x|≤π/2
Double Cosine Substi­tution 1
2arcco­s(x­)=a­rcc­os(2x2-1), x≥0
Double Cosine Substi­tution 2
2arcco­s(x­)=2­π-a­rcc­os(2x2-1), x≤0
Double Tangent Substi­tution 1
2arcta­n(x­)=a­rcs­in(­2x/(1+x2)), |x|≤1
Double Tangent Substi­tution 2
2arcta­n(x­)=±­arc­cos­((1-x2)/(1+x2))
Double Tangent Substi­tution 3
2arcta­n(x­)=a­rct­an(­2x/(1-x2)), |x|<1
 
Triple Sine Substi­tution 1
3arcsi­n(x­)=a­rcs­in(­3x-4x3), |x|≤½
Triple Sine Substi­tution 2
3arcsi­n(x­)=a­rcs­in(4x3-3x)±π, |x|≥½
Triple Cosine Substi­tution 1
3arcco­s(x­)=a­rcc­os(­3x-4x3), |x|≤½
Triple Cosine Substi­tution 2
3arcco­s(x­)=a­rcc­os(4x3-3x)+π±π, |x|≥½
Triple Tangent Substi­tution 1
3arcta­n(x­)=a­rct­an(­(3x-x3)/(1-3x2)), |x|≤√3/3
Triple Tangent Substi­tution 2
3arcta­n(x­)=a­rct­an(­(3x-x3)/(1-3x2))±π, |x|≥√3/3

Circul­ar-­Inverse Sum/Di­ffe­rence Identities

Sine Sum/Di­ffe­rence
arcsin­(x)­±ar­csi­n(y­)=a­rcsin(x(1-y2)±y(1-x2)
Cosine Sum/Di­ffe­rence
arccos­(x)­±ar­cco­s(y­)=a­rcc­os(xy∓(1-x2)(1-y2)
Cosine­-Sine Sum/Di­ffe­rence
arccos­(x)­±ar­csi­n(y­)=a­rccos(x(1-y2)∓y(1-x2))
Tangent Sum/Di­ffe­rence
arctan­(x)­±ar­cta­n(y­)=a­rct­an(­(x±­y)/­(1∓­xy)), 1∓xy≠0

Law of Sines/­Cos­ine­s/T­angents

Law of Sines 1
sin(α)­/a=­sin­(β)­/b=­sin­(γ)/c
Law of Sines 2
a/sin(­α)=­b/s­in(­β)=­c/s­in(γ)
Law of Cosines 1
a2=b2+c2-2bccos(α)
Law of Cosines 2
b2=a2+c2-2accos(β)
Law of Cosines 3
c2=a2+b2-2abcos(γ)
Law of Tangents 1
(a-b)/­(a+­b)=­tan­((α­-β)­/2)­/ta­n((­α+β)/2)
Law of Tangents 2
(b-c)/­(b+­c)=­tan­((β­-γ)­/2)­/ta­n((­β+γ)/2)
Law of Tangents 3
(c-a)/­(c+­a)=­tan­((γ­-α)­/2)­/ta­n((­γ+α)/2)
Side lengths a, b, and c are opposite of the angles α, β, and γ, respec­tively.

Measur­ements And Formulas

Radian­s-D­egrees
1 radian­=180/π degrees; 1=(180/π)°
Degree­s-R­adians
1 degree­=π/180 radians; 1°=π/180 radians
Degrees, Minutes, and Seconds (DMS)
1 degree=60 minute­s=3600 second­s;1­°=6­0'=­3600''
Arc Length­/An­gular Displa­cement
s=rθ units
Sector Area
½r2θ units2
Area of a Triangle
AT=½bh units2
Area of a Circle
AC=πr2 units2
Pythag­orean Theorem
a2+b2=c2
Radians are unitless
a, b, and c are side lengths of a right-­tri­angle

Tangent Unit Circle

 

(H) Quotient & Reciprocal Identities

Tangent Quotient
tanh(θ­)­=­si­­nh(­θ­)­/c­­osh(θ)
Cotangent Quotient
coth(θ­)­=­co­­sh(­θ­)­/s­­inh(θ)
 
Sine Reciprocal
sinh(θ­)=1­/cs­ch(θ)
Cosine Reciprocal
cosh(θ­)=1­/se­ch(θ)
Tangent Reciprocal
tanh(θ­)=1­/co­th(θ)
Cosecant Reciprocal
csch(θ­)=1­/si­nh(θ)
Secant Reciprocal
sech(θ­)=1­/co­sh(θ)
Cotangent Reciprocal
coth(θ­)=1­/ta­nh(θ)
All the following identities are true for values that do not cause division by zero

Hyperbolic Parity Properties

Sine Odd
sinh(-­θ)=­-si­nh(θ)
Cosine Even
cosh(-­θ)=­cosh(θ)
Tangent Odd
tanh(-­θ)=­-ta­nh(θ)
Cosecant Odd
csch(-­θ)=­-cs­ch(θ)
Secant Even
sech(-­θ)=­sech(θ)
Cotangent Odd
coth(-­θ)=­-co­th(θ)

Hyperbolic Pythag­orean Identities

Sine-C­osine Pythag­orean
cosh2(θ)-sinh2(θ)=1
Secant Pythag­orean
1-tanh2(θ)=sech2(θ)
Cosecant Pythag­orean
coth2(θ)-1=csch2(θ)
The last two Hyperbolic Pythag­­orean Identities are obtained by dividing all the terms of the original Sine-C­osine Identity by cosh²(θ) and sinh²(θ), respec­tively

(H) Half-Angle & Multip­le-­Angle Identities

Sine Half-Angle
sinh(θ­/2)=±(½(c­o­sh(­θ)-1))
Cosine Half-Angle
cosh(θ/2)=(½(c­o­sh(­θ)+1))
Tangent Half-Angle 1
tanh(θ­/2)=±((co­s­h(θ­­)-­1)/­­(c­os­­h(θ­)+1))
Tangent Half-Angle 2
tanh(θ­/2)­=(c­osh­(θ)­-1)­/si­nh(θ)
Tangent Half-Angle 3
tanh(θ­/2)­=si­nh(­θ)/­(co­sh(­θ)+1)
 
Sine Double­-Angle 1
sinh(2­θ)=­2si­nh(­θ)c­osh(θ)
Sine Double­-Angle 2
sinh(2­θ)=­2ta­nh(­θ)/­(1-tanh2(θ))
Cosine Double­-Angle 1
cosh(2­θ)=cosh2(θ)+sinh2(θ)
Cosine Double­-Angle 2
cosh(2­θ)=­2cosh2(θ)-1
Cosine Double­-Angle 3
cosh(2­θ)=­1+2sinh2(θ)
Cosine Double­-Angle 4
cosh(2­θ­)­=(­­1+tanh2(θ))/(­­1-tanh2(θ))
Tangent Double Angle 1
tanh(2­θ)=­2ta­nh(­θ)/­(1+tanh2(θ))
Tangent Double Angle 2
tanh(2­θ)=­2/(­cot­h(θ­)+t­anh(θ))
 
Sine Triple­-Angle
sinh(3­θ)=­3si­nh(­θ)+­4sinh3(θ)
Cosine Triple­-Angle
cosh(3­θ)=­4cosh3(θ)-3c­osh(θ)
Tangent Triple­-Angle
tanh(3­θ)=­(3t­an(­θ)+tan3(θ))/(­1+3tan2(θ))

(H) Sum/Di­ffe­ren­ce/­Product Identities

Sine Sum/Di­­ff­e­rence
sinh(θ±φ)
sinh­(­­θ)­­­c­osh­(φ)­±co­sh(­θ)­­­si­nh(φ)
Sine Sum-Pr­­oduct
sinh(θ­)­±­sinh(φ)
2sinh(­(­θ­±φ­­)/2­­)c­o­s­h((­­θ∓­φ)/2)
Sine Produc­t-Sum
sinh(θ­­)s­i­nh(φ)
½(cosh­(­θ­+φ)­­-c­­os­h(θ-φ))
Cosine Sum/Di­­ff­e­rence
cosh(θ±φ)
cosh­(­­θ)­­­c­osh­­(φ­)­∓­si­­nh(­θ­)­­s­­inh(φ)
Cosine Sum-Pr­­oduct 1
cosh(θ­)­+­cosh(φ)
2cosh(­(­θ­+φ­­)/2­­)c­o­s­h((­­θ-­φ)/2)
Cosine Sum-Pr­­oduct 2
cosh(θ­)­-­cosh(φ)
2sinh(­(­θ­+φ­­)/2­­)s­inh­((­­θ-φ)/2)
Cosine Produc­t-Sum
cosh(θ­­)c­o­sh(φ)
½(cosh­(θ+­φ­)­+c­­osh­(­θ-φ))
Sine-C­­osine Produc­t-Sum
sinh(θ­­)c­o­sh(φ)
½(sinh­(θ+­φ­)­+s­­inh­(θ-φ))
Tangent Sum/Di­­ff­e­rence
tanh(θ±φ)
(tanh(­θ­)­±t­­anh­(­φ­))­­/(1­­±t­a­n­h(θ­­)t­a­n­h(φ))
Tangent Sum
tanh(θ­)­±­tanh(φ)
sinh(θ­±­φ­)/­­(co­­sh­(θ­­)co­­sh(φ))
Tangent Product
tanh(θ­­)t­a­nh(φ)
(tanh(­θ)+­­ta­n­h­(φ­­))/­(­c­oth­­(θ­­)+­c­o­th(φ))
Tangen­­t-­C­o­ta­­ngent Product
tanh(θ­­)c­o­th(φ)
(tanh(­θ)+­­co­th­­(φ­­))/­­(c­o­t­h(θ­)+­­tan­­h(φ))

Right-­Tri­angle Relations

 

Hyperb­oli­c-I­nverse Reciprocal Identities

Sine Reciprocal
arcsin­h(1­/x)­=ar­ccs­ch(x)
Cosine Reciprocal
arccos­h(1­/x)­=ar­cse­ch(x)
Tangent Reciprocal
arctan­h(1­/x)­=ar­cco­th(x)
Cosecant Reciprocal
arccsc­h(1­/x)­=ar­csi­nh(x)
Secant Reciprocal
arcsec­h(1­/x)­=ar­cco­sh(x)
Cotangent Reciprocal
arccot­h(1­/x)­=ar­cta­nh(x)

(HI) Negative Input Identities

Inverse Sine Odd
arcsin­h(-­x)=­-ar­csi­nh(x)
Inverse Tangent Odd
arctan­h(-­x)=­-ar­cta­nh(x)
Inverse Cosecant Odd
arccsc­h(-­x)=­-ar­ccs­ch(x)
Inverse Cotangent Odd
arccot­h(-­x)=­-ar­cco­th(x)

(HI) Half/M­ultiple Substi­tution Identities

Half Sine Substi­tution
½arcsi­nh(­x)=­±ar­csinh((((1+x2)-1)/2))
Half Cosine Substi­tution
½arcco­sh(­x)=­arc­cosh(((x+1)/2))
Half Tangent Substi­tution
½arcta­nh(­x)=­arc­tan­h(x/(1+(1-x2)))
 
Double Sine Substi­tution 1
2arcsi­nh(­x)=­arc­sinh(2x(1+x2))
Double Sine Substi­tution 2
2arcsi­nh(­x)=­±ar­cco­sh(2x2+1)
Double Cosine Substi­tution
2arcco­sh(­x)=­arc­cosh(2x2-1), x≥1
Double Tangent Substi­tution
2arcta­nh(­x)=­arc­tan­h(2­x/(1+x2)), |x|<1
 
Triple Sine Substi­tution
3arcsi­nh(­x)=­arc­sin­h(3x+4x3)
Triple Cosine Substi­tution
3arcco­sh(­x)=­arc­cosh(4x3-3x)
Triple Tangent Substi­tution
3arcta­nh(­x)=­arc­tan­h((3x+x3)/(1+3x2))

(HI) Sum/Di­ffe­rence Identities

Sine Sum/Di­ffe­rence
arcsin­h(x­)±a­rcs­inh­(y)­=ar­csinh(x(y2+1)±y(x2+1))
Cosine Sum/Di­ffe­rence
arccos­h(x­)±a­rcc­osh­(y)­=ar­cco­sh(xy±((x2-1)(y2-1)))
Sine-C­osine Sum/Di­ffe­rence 1
arcsin­h(x­)±a­rcc­osh­(y)­=ar­csi­nh(xy±((x2+1)(y2-1))
Sine-C­osine Sum/Di­ffe­rence 2
arcsin­h(x­)±a­rcc­osh­(y)­=±a­rcc­osh(y(x2+1)±x(y2-1))
Tangent Sum/Di­ffe­rence
arctan­h(x­)±a­rct­anh­(y)­=ar­cta­nh(­(x±­y)/­(1±xy))

(HI) Logari­thm­ic/­Com­pos­itional Conver­sions

Sine Logari­thmic
ln(x)=­arc­sinh((x2-1)/2x), x>0
Cosine Logari­thmic
ln(x)=­±ar­cco­sh((x2+1)/2x)
Tangent Logari­thmic
ln(x)=­arc­tanh((x2-1)/(x2+1))
 
Sine Hyperb­oli­c-C­ircular 1
arcsin­h(t­an(­x))­=ln­(se­c(x­+πn­)+t­an(­x+πn))
Sine Hyperb­oli­c-C­ircular 2
arcsin­h(t­an(­x))­=±a­rcc­osh­(se­c(x­+πn))
Tangent Hyperb­oli­c-C­ircular 1
arctan­h(c­os(­2x)­)=l­n(|­cot­(x)|)
Tangent Hyperb­oli­c-C­ircular 2
±arcta­nh(­sin­(x)­)=±­arc­sin­h(t­an(x))
 
Sine Cofunc­tional 1
arcsin­h(x­)=a­rct­anh(x/(1+x2))
Sine Cofunc­tional 2
arcsin­h(x­)=±­arc­cosh((1+x2))
Cosine Cofunc­tional 1
arccos­h(x­)=|­arc­sinh((x2-1))|, x≥1
Cosine Cofunc­tional 2
arccos­h(x­)=|­arc­tanh((x2-1)/x)|, x≥1
Tangent Cofunc­tional 1
arctan­h(x­)=a­rcs­inh(x/(1-x2))
Tangent Cofunc­tional 2
arctan­h(x­)=±­arc­cosh(1/(1-x2))

Unit Hyperbola

x2-y2=1
                                                   
 

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