Compound angle formula and Multiple angle formula

Addition angles

Angles in the form (A + B) or (A – B)

Double angles

Angles in the form 2A, 3A ,…

sin (A + B) = sin A cos B + cos A sin B

sin (A – B) = sin A cos B – cos A sin B

cos (A + B) = cos A cos B – sin A sin B

cos (A – B) = cos A cos B + sin A sin B

sin 2A = 2 sin A cos A

cos 2A = 1 – 2 sin2 A

Half-angle formulae

Addition formulae

-can be used to prove the other trigonometric identities -can be used to derive double-angle formulae