Sum to product formula: sin A − sin B
sin A − sin B = 2 cos((A + B)/2) sin((A − B)/2). The sine and cosine swap places compared with the sum version - the half-sum takes the cosine and the half-difference takes the sine.
Related Sum to Product identities
Common questions
What is the sin A − sin B identity?
sin A − sin B = 2 cos((A + B)/2) sin((A − B)/2). The sine and cosine swap places compared with the sum version - the half-sum takes the cosine and the half-difference takes the sine.
Which identities are related to sin A − sin B?
sin A − sin B belongs to the Sum to Product group. The identities used alongside it most often are sin A + sin B, cos A + cos B and cos A − cos B.
Practise it
Reading a formula is not the same as recalling it under time pressure. The workspace drills Sum to Product questions in the quiz, and the triangle solver shows a worked solution for any triangle you type in.
Or browse all 45 identities in the full reference, or read the trigonometry guides for the method behind them.