
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 the book "Mathematical Treatise in Nine Sections" volume five, "Field Mathematics", written by Qin Jiushao, a famous mathematician from the Southern Song Dynasty, there is a problem: "There is a piece of triangular sand field with three sides measuring 13 li, 14 li, and 15 li (1 li equals 500 meters). What is the area of this sand field in square kilometers?"

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