Back to Trigonometric Identities
Angle Sum Identities
Identity Type
Formula
Sine
\[ \sin(x + y) = \sin x \cos y + \cos x \sin y \]
Cosine
\[ \cos(x + y) = \cos x \cos y - \sin x \sin y \]
Tangent
\[ \tan(x + y) = \frac{\tan x + \tan y}{1 - \tan x \tan y} \]