
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
Given point $F$ is the left focus of the hyperbola $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1 (a > 0, b > 0)$, and point $E$ is the right vertex of this hyperbola. A line passing through point $F$ and perpendicular to the $x$-axis intersects the hyperbola at points $A$ and $B$. If $\triangle ABE$ is a right triangle, find the eccentricity of this hyperbola.

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