Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Conway's Nightmare: Brahmagupta and Butterflies   This note gives a very succinct conceptual proof of Brahmagupta's formula for
cyclic quadrilaterals, and then a long discussion about how the proof is
inspired by ideas from modern mathematics.

35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph