I have a simple trig equation of
$cos(θ/2)=0.382$ and I'm trying to solve for theta, The correct value should be 0.37 radians for theta, but I can't seem to figure out how to get this, I tried doing the inverse cos of 0.382 but that gave me 1.18 radians instead, even if I divided that by 2 it's still not anything near 0.37.
What am I doing wrong?
EDIT: to clarify this question is from my quantum computing class on Qubits, this is one of the solutions to exercises I'm supposed to do: 
we are supposed to solve get the directions of the vectors on a bloch sphere given the qubit state, which is basically just solving for theta and phi, I don't think this should affect the trig part though, could the answer possibly be wrong?
Given that $\cos(0.37/2) \approx 0.983$ and that $0.983 \neq 0.382$, clearly the correct answer isn't going to be $\theta = 0.37$.
Your professor probably just made a mistake when writing the exercise. A correct solution to $\cos(\theta/2) = 0.382$ is $\theta \approx 2.3577$.