
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
There are two circles: one centered at point \(A\) with a radius of 5, and another centered at point \(B\) with a radius of 15. Their common internal tangent touches the circles at points \(C\) and \(D\) respectively. The lines \(AB\) and \(CD\) intersect at point \(E\). Find \(CD\) if \(BE = 39\).

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