
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
A line passing through the focus \( F \) of a parabola intersects the parabola at points \( A \) and \( B \). If the projections of \( A \) and \( B \) onto the directrix of the parabola are \( A_1 \) and \( B_1 \) respectively, what is the measure of \( \angle A_1 F B_1 \)?

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