Find v and a if $\displaystyle z = \cos{(2t)} + i\sin{(2t)}$.

I understand that:

$\displaystyle \frac{dz}{dt} = \frac{dx}{dt} + i\frac{dy}{dt}$

And similarly for the acceleration derivative.

I'm just not 100% sure that the velocity and acceleration I got are correct, especially the acceleration.