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Digital control systems and root locus

I have been trying to work through a problem and see how its done but Im not sure where the angles of 17.10 -138.52 -109.84 = -231.26 come from.

I have attached the matlab root locus plot and the plot from the example also the ZOH transfer function is there and the dominant poles.

I printed it out and plotted the dominant poles but the angles didnt add up to -231.26

Can anyone suggest why and what Im doing wrong?
 

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