
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
Given that the side AB of ∆ABC is divided into n equal parts (n > 1990), through the n-1 division points, lines parallel to BC are drawn intersecting AC at points Bi, Ci respectively for i = 1, 2, 3, …, n-1, determine the ratio of the area of ∆AB1C1 to the area of the quadrilateral B1989 B1990 C1990 C1989.

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