
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
Four coplanar squares with side lengths of 3, 5, 7, and 9 units, respectively, are placed sequentially, each sharing one side lying on line $CD$. A segment connects the bottom left corner of the smallest square to the upper right corner of the largest square. What is the area of the shaded trapezoid formed by this segment, the line $CD$, and the sides of the smallest and the largest squares?

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