
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 right vertex of the ellipse $C: \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 (a > b > 0)$ is $A$. A line $l$ passing through the origin intersects the ellipse $C$ at points $P$ and $Q$. If $|PQ| = a$ and $AP \perpendicular PQ$, then the eccentricity of the ellipse $C$ is ______.

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