
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 in $\triangle ABC$, $b(\sin B+\sin C)=(a-c)(\sin A+\sin C)$ where angles $A$, $B$, $C$ are opposite to sides $a$, $b$, $c$ respectively, and $\angle B$ is an obtuse angle.  
(1) Find the size of angle $A$;  
(2) If $a= \frac { \sqrt {3}}{2}$, find the range of values for $b+c$.

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