
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 $(a+b+c)(a-b+c)=3ac$.
1. Find the measure of angle $B$.
2. Given that $ac=\frac{2}{3}b^2$, and the radius of the circumcircle of $\triangle ABC$ is $\sqrt{3}$, with $a<c$, find the value of $\overrightarrow{AC}\cdot\overrightarrow{AB}$.

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