Angle Identities

Double Angle Formula for Cosine 3

cos(2a)= 1-2sin^2(a)

Double Angle Formula for Cosine 2

cos(2a)= 2cos^2(a)-1

Double Angle Formula for Cosine 1

cos(2a)= cos^2(a)-sin^2(a)

Angle Sum Identity for Cosine

cos(a+B)= cos(a)cos(B)-sin(a)sin(B)

Angle Difference Identity for Cosine

cos(a-B)= cos(a)cos(B)+sin(a)sin(B)

Double Angle Formula for Sine

sin(2a)= 2sin(a)cos(a)

Angle Sum Identity for Sine

sin(a+B)= sin(a)cos(B)+cos(a)sin(B)

Angle Difference Identity for Sine

sin(a-B)= sin(a)cos(B)-cos(a)sin(B)