
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 trapezoid \(ABCD\), \(BC\) is parallel to \(AD\), \(AB = AD\), \(\angle ABC = \frac{2\pi}{3}\), and \(\angle BCD = \frac{\pi}{2}\). \(\triangle ABD\) is folded along \(BD\) such that point \(A\)'s projection onto plane \(BCD\) is point \(P\). Given that the cosine of the angle between \(AB\) and \(CD\) is \(\frac{\sqrt{3}}{6}\), find the cosine of the angle between \(BP\) and \(CD\).

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