Sum and Difference Identities

• sin(x+y) = sin(x)cos(y)+cos(x)sin(y)
• cos(x+y) = cos(x)cos(y)–sin(x)sin(y)
• t a n ( x + y ) = t a n   x + t a n   y / 1 − t a n   x . t a n   y

• sin(x–y) = sin(x)cos(y)–cos(x)sin(y)
• cos(x–y) = cos(x)cos(y) + sin(x)sin(y)

t a n ( x − y ) = t a n   x − t a n   y / 1 + t a n   x . t a n   y