Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Simple Vector Proof of Feuerbach's Theorem   The celebrated theorem of Feuerbach states that the nine-point circle of a
nonequilateral triangle is tangent to both its incircle and its three
excircles. In this note, we give a simple proof of Feuerbach's Theorem using
straightforward vector computations. All required preliminaries are proven here
for the sake of completeness.

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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an