Quadrilateral with given angles

geometry

If you are looking for the proof by elementary geometry, please see Hiroshi Saito(斉藤浩)'s great work about generalized Langley's problem ( https://www.gensu.co.jp/saito/challenge/pdf/3circumcenter_d20180609.pdf ). He introduced the amazing skill named "3 circumcenter method" invented by Ms. aerile_re(pen name), and you can find the solution of this problem in the article (Q1).


my geometric solution: http://www.davdata.nl/math/geopuzzle28.html

arc calculation

arc calculation(2)

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