Complex numbers help please

[drunkgenie]

I’ve done a maths question however I’m unsure as to whether my workings are correct, I would really if someone could check my answers and tell me whether I’m on the right track or where I went wrong. Any help would be appreciated.
The question is as follows:
In control engineering, a discrete-time system has the following closed-loop transfer function:
G(z)=0.5(3z^3+2)/(z^4+0.5z+1)
,
where z is complex.


c) Let z = jθ, where θ is measured in radians, and consider G(z) = G(j θ), The terms |G(jθ)| and arg(G(jθ)), measured in radians, are known as the amplitude and phase response of the system, respectively. Find the amplitude and phase response when θ = 1.


G =

0.2941 - 0.8235i

r =

0.8745


theta =

-1.2278

[jemidiah]

You're correct.

[drunkgenie]

okeydok, thankyou