A condition for a circumscriptible quadrilateral to be cyclic - Mowaffaq Hajja We give a short proof of a characterization, given by M. Radic et al, of convex quadrilaterals that admit both an incircle and a circumcircle. ✪ ✪ ✪ ✪ ✪ Link tải tài liệu: LINK TẢI TÀI LIỆU Theo LTTK Education