
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
In triangle $\triangle ABC$, sides a, b, and c are opposite to angles A, B, and C, respectively. Given $\vec{m} = (a-b, c)$ and $\vec{n} = (a-c, a+b)$, and that $\vec{m}$ and $\vec{n}$ are collinear, find the value of $2\sin(\pi+B) - 4\cos(-B)$.

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