Answer and explanation :
We have to prove [tex]sin(A-B)=sinAcosB-cosAsinB[/tex] by using sum formula
We know that [tex]sin(A+B)=sinAcosB+cosAsinB[/tex]
Now replace B = -B
So [tex]sin(A+(-B))=sinAcos(-B)+cosAsin(-B)[/tex]
We know that [tex]cos(-B)=cos(B)\ and \ and\ sin(-B)=-sinB[/tex]
So [tex]sin(A-B)=sinAcosB-cosAsinB[/tex] which we have to prove