Question

Sin(A+B) - sin(A-B) = 2cos A sin BProve that answer please , I'm stuck​

Answer 1

Answer:

Step-by-step explanation:

Hello,

I assume that you know that

$sin(A+B)=sinAcosB+cosAsinB\\\\sin(A-B)=sinAcosB-cosAsinB$

One way to retrieve them quickly is to use Euler's formula and then,

$cos(A+B)+isin(A+B)=e^{i(A+B)}=e^{iA}e^{iB}=(cosA+isinA)(cosB+isinB)$

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