
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 $ABC$, the sides opposite angles $A$, $B$, $C$ are $a$, $b$, $c$ respectively. It is known that $2\cos A (b \cos C + c \cos B) = a$.
(1) Find the value of angle $A$;
(2) If $\cos B = \frac{3}{5}$, find the value of $\sin(B - C)$.

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