Trig Identities

Reciprocal Identities §

csc x = sec x = cot x =

Quotient Identities §

= tan x = cot x

Reciprocal Identities §

Square both sides csc x = sec x = cot x =

Pythagorean Identities §

sinx + cosx = 1 Rearrange the identity sin x = 1 - cos x cos x = 1 - sin x

1 + cot x = csc x tan x + 1 = sec x

Co-Function Identities §

sin( - x) = cos x csc( - x) = sec x cos( - x) = sin x sec( - x) = csc x tan( - x) = cot x cot( - x) = tan x

Even-odd identities §

sin(-x) = - sin x csc(-x) = - csc x cos(-x) = cos x sec(-x) = sec x tan(-x) = - tan x cot(-x) = - cot x

Sum-Difference formulas §

sin(x y) = sin x cos y cos x sin y cos(x y) = cos x cos y sin x sin y tan(x y) =

Double Angle Formulas §

sin(2x) = 2 sin x cos x cos(2x) = cos x - sin x = 2 cos x - 1 = 1 - 2sin x tan(2x) =