Trigonometry

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Important Maths Formulas: Trigonometric Ratios and Identities

Trigonometric Ratios trigonometry_right trianglesin theta

Cos theta

 

tan theta

Trigonometric Ratios of Standard Angles value of trigonometric ratios
Tangent Identities  tan identity

cot identity

Reciprocal Identities Reciprocal identities
Pythagorean Identities sin2θ + cos2θ = 1

tan2 θ + 1 = secθ

cot2θ + 1 = cosec2θ

Even/Odd Identities sin(-θ) = -sin θ

cos(-θ) = cos θ

tan(-θ) = -tanθ

cosec(-θ) = -cosec θ

sec(-θ) = sec θ

cot(-θ) = -cot θ

Periodic Identities sin(θ  + 2πn) = sin θ

cos(θ + 2πn) = cos θ

tan(θ + πn) = tan θ

cosec(θ + 2πn) = cosec θ

sec(θ + 2πn) = sec θ

cot(θ + πn) = cot θ

Cofunction Identities sin(π/2 - θ) = cos θ

cos(π/2 - θ) = sin θ

tan(π/2 - θ) = cot θ

cosec(π/2 - θ) = sec θ

sec(π/2 - θ) = cosec θ

cot(π/2 - θ) = tan θ

Half Angle Identities  Half angle identities
Double Angle Identities  Double angle identities
Product to Sum Identities  Product to sum identities
Sum to Product Identities  sum to product identities
Sum/Difference Identities  law of cosines
Law of Sines  law of sines
Law of Cosines  law of cosines