
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 $\overrightarrow{m} = (\sin B, 1-\cos B)$ and $\overrightarrow{n} = (2, 0)$, and the angle between $\overrightarrow{m}$ and $\overrightarrow{n}$ is $\frac{\pi}{3}$, where A, B, C are the internal angles of $\triangle ABC$.  
(1) Find the magnitude of angle B;  
(2) Determine the range of values for $\sin A + \sin C$.

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