The teachers’ library›TrigonometrySum-to-product formulassinA+sinB=2sin2A+Bcos2A−BsinA+sinB=2sinA+B2cosA−B2sinA−sinB=2cos2A+Bsin2A−BsinA−sinB=2cosA+B2sinA−B2cosA+cosB=2cos2A+Bcos2A−BcosA+cosB=2cosA+B2cosA−B2cosA−cosB=−2sin2A+Bsin2A−BcosA−cosB=−2sinA+B2sinA−B2Open on a new board The board is kept in this browser only, like your other boards. On any board, the Library button adds this too.More in TrigonometrySOH CAH TOAPythagorean identitiesReciprocal trigonometric functionsExact valuesCompound angle formulasDouble angle formulasHalf-angle and power-reducing formulasCofunction and symmetry identitiesGeneral solutions of trigonometric equationsRadians and degrees