
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 sides of lengths 1, 3, 5, and 7 units, respectively, are arranged side-by-side, such that one side of each square lies on line $AB$, and a segment connects the bottom left corner of the smallest square to the upper right corner of the largest square. Calculate the area of the shaded trapezoid formed in this arrangement.

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