
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 to angles $A$, $B$, and $C$ are $a$, $b$, and $c$ respectively, and $$\frac{ \sqrt{3}\sin B−\sin C}{b−a}$$ = $$\frac{\sin A+\sin B}{c}$$.
(1) Find the measure of angle $A$;
(2) If the common difference of the arithmetic sequence ${a_n}$ is not zero, $a_1\sin A=1$, and $a_2$, $a_4$, $a_8$ form a geometric sequence; if $b_n$ = $$\frac{1}{{a}_{n}{a}_{n+1}}$$, find the sum $S_n$ of the first $n$ terms of the sequence ${b_n}$.

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