Answer:
Step-by-step explanation:
Hello,
I assume that you know that
[tex]sin(A+B)=sinAcosB+cosAsinB\\\\sin(A-B)=sinAcosB-cosAsinB[/tex]
One way to retrieve them quickly is to use Euler's formula and then,
[tex]cos(A+B)+isin(A+B)=e^{i(A+B)}=e^{iA}e^{iB}=(cosA+isinA)(cosB+isinB)[/tex]
and you can replace B by -B for the second formula.
So, it comes that sin(A+B)-sin(A-B)=2cosAsinB
Hope this helps
