Answer:
Vz = arccos(0.1673413807) = 80.37º
Explanation:
The inverse function of the cosine is the arc cosine.
That means, that if we have that cos a = 1, a is the angle which has cosine equals 1, so a = arccos(1) = 0º.
In this problem, we have that:
cos(Vz) = 0.1673413807
Vz = arccos(0.1673413807) = 80.37º