$\theta_{s}=\frac{\pi}{12}$

Step 1 ：Given that $\theta_{s} = \frac{\pi}{12}$

Step 2 ：Calculate the value of $\frac{\pi}{12}$ in radians

Step 3 ：\(\theta_{s} = 0.2618\) radians (approximately)

Step 4 ：\(\boxed{\theta_{s} = 0.2618}\)