Thread: verify Euler's sine and cosine Identity

sine(x)= 1/2i(e^ix -e^-ix) and cos(x)=1/2i(e^ix + e^-ix)

I am supposed to verify these identities. I know that e^ix = cos x + i sin x.
So do I plug that in and simplify or is there something that I am missing?

Yes, plug that in and use some trig identities. The most useful one will be that .