
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 $\triangle ABC$, $A$, $B$, $C$ are the three interior angles, and $a$, $b$, $c$ are the lengths of the sides opposite these angles, respectively. It is given that $b^{2}+c^{2}-a^{2}=bc$.

$(1)$ Find the measure of angle $A$;  
$(2)$ If $\sin^{2}A+\sin^{2}B=\sin^{2}C$, find the measure of angle $B$.

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