
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 his work "Mathematical Treatise in Nine Sections" Volume 5 "Types of Fields," Qin Jiushao, a famous mathematician from the Southern Song Dynasty of China, posed a question: "There is a triangular sand field with three sides. The shortest side is 13 li, the middle side is 14 li, and the longest side is 15 li. Assuming 1 li is equivalent to 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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