Question

sin(a+b)cosb - sinb*cos(a+b)

Answer 1

sin(a-b)+2cosa*sinb=sinacosb-cosasinb+2cosasinb=sin(a+b)

2cosa*cosb-cos(a-b)=2cosacosb-cosacosb-sinasinb=cos(a+b)

sin(a+b)/cos(a+b)=tg(a+b)