Circular Quotient & Reciprocal Identities
Tangent Quotient |
tan(θ)=sin(θ)/cos(θ) |
Cotangent Quotient |
cot(θ)=cos(θ)/sin(θ) |
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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)) |
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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)) |
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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
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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)) |
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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 |
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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
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(H) Quotient & Reciprocal Identities
Tangent Quotient |
tanh(θ)=sinh(θ)/cosh(θ) |
Cotangent Quotient |
coth(θ)=cosh(θ)/sinh(θ) |
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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) |
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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)) |
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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
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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))) |
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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 |
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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)) |
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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)) |
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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)) |
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