
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
Two circles touch each other externally at point \( A \). Their common tangent touches the first circle at point \( B \) and the second circle at point \( C \). The line passing through points \( A \) and \( B \) intersects the second circle at point \( D \). It is known that \( AB = 5 \) cm, \( AD = 4 \) cm. Find \( CD \).

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