
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
Cyclic pentagon  $ ABCDE$  has a right angle  $ \angle{ABC} \equal{} 90^{\circ}$  and side lengths  $ AB \equal{} 15$  and  $ BC \equal{} 20$ . Supposing that  $ AB \equal{} DE \equal{} EA$ , find  $ CD$ .

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