
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
The two vertices of the ellipse $\frac{x^2}{a^2}+\frac{y^2}{b^2}=1(a>b>0)$ are $A\left(a,0\right)$ and $B\left(0,b\right)$, and the left focus is $F$. In $\triangle FAB$, $\angle B=90^{\circ}$. Find the eccentricity of the ellipse.

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