
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
Construct the triangle $ABC$ given the side $BC = a$, the median $BB_1 = s_b$ (where $B_1$ is the midpoint of the side $AC$), and the angle $\angle ABB_1 = \beta_2$.

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