
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
In triangle $DEF$, the side lengths $d$, $e$, and $f$ satisfy $d + 3e + 3f = d^2$ and $d + 3e - 3f = -5.$ Determine the largest angle of triangle $DEF$, where $d$ is the side length opposite $\angle D$.

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