Pine Crest School Pre-Calculus Honors Handy Dandy Trigonometric Identities Reference Sheet RECIPROCAL IDENTITIES QUOTIENT IDENTITIES PYTHAGOREAN IDENTITIES sin2 x + cos2 x = 1 1 + cot2 x = csc2 x tan2 x + 1 = sec2 x SYMMETRY IDENTITIES cos (?x) = cos x sin (?x) = ? sin x tan (?x) = ? tan x CO-FUNCTION IDENTITIES = sin x = csc x = tan x ANGLE SUM IDENTITIES sin(x + y) = sin x cos y + cos x sin y sin(x ? y) = sin x cos y ? cos x sin y cos(x+y) = cos x cos y ? sin x sin y cos(x ? y) = cos x cos y + sin x sin y DOUBLE ANGLE IDENTITIES sin 2x = 2 sin x cos x cos 2x = cos2x ? sin2x = 2 cos2x ? 1 = 1 ? 2 sin2x HALF ANGLE IDENTITIES

# Trig Identities

Pine Crest School Pre-Calculus Honors Handy Dandy Trigonometric Identities Reference Sheet RECIPROCAL IDENTITIES QUOTIENT IDENTITIES PYTHAGOREAN IDENTITIES sin2 x + cos2 x = 1 1 + cot2 x = csc2 x tan2 x + 1 = sec2 x SYMMETRY IDENTITIES cos (?x) = cos x sin (?x) = ? sin x tan (?x) = ? tan x CO-FUNCTION IDENTITIES = sin x = csc x = tan x ANGLE SUM IDENTITIES sin(x + y) = sin x cos y + cos x sin y sin(x ? y) = sin x cos y ? cos x sin y cos(x+y) = cos x cos y ? sin x sin y cos(x ? y) = cos x cos y + sin x sin y DOUBLE ANGLE IDENTITIES sin 2x = 2 sin x cos x cos 2x = cos2x ? sin2x = 2 cos2x ? 1 = 1 ? 2 sin2x HALF ANGLE IDENTITIES

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