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Double Angle Identities

Double Angle Identities
Double Number Identities

Trig identities that show how to find the sine, cosine, or tangent of twice a given angle.

 

Double Angle Identities

Math formula: sin 2x = 2 sin x cos x, the double angle identity for sine.

cos 2x equals three equivalent forms: cos²x − sin²x, 1 − 2sin²x, and 2cos²x − 1

tan(2x) = (2·tan x) / (1 − tan²x)

 

See also

Half angle identities