A. Bogomolny, An Identity in (Cyclic) Quadrilaterals, Interactive Mathematics Miscellany and Puzzles,
[1]Архивная копия от 28 мая 2019 на Wayback Machine, Accessed 18 March 2014.
A. Bogomolny, An Identity in (Cyclic) Quadrilaterals, Interactive Mathematics Miscellany and Puzzles,
[1]Архивная копия от 28 мая 2019 на Wayback Machine, Accessed 18 March 2014.