
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Given vectors $\overrightarrow{OA}=(\lambda\sin \alpha,\lambda\cos \alpha)$ and $\overrightarrow{OB}=(\cos \beta,\sin \beta)$, with $\alpha+\beta=\frac{5\pi}{6}$, where $O$ is the origin.  
(Ⅰ) If $\lambda < 0$, find the angle between vectors $\overrightarrow{OA}$ and $\overrightarrow{OB}$.  
(Ⅱ) If $\lambda\in[-2,2]$, find the range of values for $|\overrightarrow{AB}|$.

Present the answer in LaTex format: \boxed{Your answer}
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